diff --git a/.eslintrc b/.eslintrc
index 9177344c..a1646659 100644
--- a/.eslintrc
+++ b/.eslintrc
@@ -12,5 +12,10 @@
     "react/no-find-dom-node": "warn",
     "react/no-render-return-value": "warn",
     "react/no-deprecated": "warn"
+  },
+  "globals": {
+    "FileReader": true,
+    "localStorage": true,
+    "fetch": true
   }
 }
diff --git a/browser/components/CodeEditor.js b/browser/components/CodeEditor.js
index c7b54b2d..d944ed18 100644
--- a/browser/components/CodeEditor.js
+++ b/browser/components/CodeEditor.js
@@ -103,7 +103,7 @@ export default class CodeEditor extends React.Component {
     this.editor.on('change', this.changeHandler)
     this.editor.on('paste', this.pasteHandler)
 
-    let editorTheme = document.getElementById('editorTheme')
+    const editorTheme = document.getElementById('editorTheme')
     editorTheme.addEventListener('load', this.loadStyleHandler)
 
     CodeMirror.Vim.defineEx('quit', 'q', this.quitEditor)
@@ -121,7 +121,7 @@ export default class CodeEditor extends React.Component {
     this.editor.off('blur', this.blurHandler)
     this.editor.off('change', this.changeHandler)
     this.editor.off('paste', this.pasteHandler)
-    let editorTheme = document.getElementById('editorTheme')
+    const editorTheme = document.getElementById('editorTheme')
     editorTheme.removeEventListener('load', this.loadStyleHandler)
   }
 
@@ -197,7 +197,7 @@ export default class CodeEditor extends React.Component {
   }
 
   setValue (value) {
-    let cursor = this.editor.getCursor()
+    const cursor = this.editor.getCursor()
     this.editor.setValue(value)
     this.editor.setCursor(cursor)
   }
@@ -222,7 +222,7 @@ export default class CodeEditor extends React.Component {
     if (!dataTransferItem.type.match('image')) return
 
     const blob = dataTransferItem.getAsFile()
-    let reader = new FileReader()
+    const reader = new FileReader()
     let base64data
 
     reader.readAsDataURL(blob)
@@ -242,7 +242,8 @@ export default class CodeEditor extends React.Component {
   }
 
   render () {
-    let { className, fontFamily, fontSize } = this.props
+    const { className, fontSize } = this.props
+    let fontFamily = this.props.className
     fontFamily = _.isString(fontFamily) && fontFamily.length > 0
       ? [fontFamily].concat(defaultEditorFontFamily)
       : defaultEditorFontFamily
diff --git a/browser/components/MarkdownEditor.js b/browser/components/MarkdownEditor.js
index 65b52f86..b94a64a6 100644
--- a/browser/components/MarkdownEditor.js
+++ b/browser/components/MarkdownEditor.js
@@ -5,7 +5,6 @@ import CodeEditor from 'browser/components/CodeEditor'
 import MarkdownPreview from 'browser/components/MarkdownPreview'
 import eventEmitter from 'browser/main/lib/eventEmitter'
 import { findStorage } from 'browser/lib/findStorage'
-const _ = require('lodash')
 
 class MarkdownEditor extends React.Component {
   constructor (props) {
@@ -70,9 +69,9 @@ class MarkdownEditor extends React.Component {
   }
 
   handleContextMenu (e) {
-    let { config } = this.props
+    const { config } = this.props
     if (config.editor.switchPreview === 'RIGHTCLICK') {
-      let newStatus = this.state.status === 'PREVIEW'
+      const newStatus = this.state.status === 'PREVIEW'
         ? 'CODE'
         : 'PREVIEW'
       this.setState({
@@ -91,9 +90,9 @@ class MarkdownEditor extends React.Component {
   handleBlur (e) {
     if (this.state.isLocked) return
     this.setState({ keyPressed: new Set() })
-    let { config } = this.props
+    const { config } = this.props
     if (config.editor.switchPreview === 'BLUR') {
-      let cursorPosition = this.refs.code.editor.getCursor()
+      const cursorPosition = this.refs.code.editor.getCursor()
       this.setState({
         status: 'PREVIEW'
       }, () => {
@@ -109,7 +108,7 @@ class MarkdownEditor extends React.Component {
   }
 
   handlePreviewMouseUp (e) {
-    let { config } = this.props
+    const { config } = this.props
     if (config.editor.switchPreview === 'BLUR' && new Date() - this.previewMouseDownedAt < 200) {
       this.setState({
         status: 'CODE'
@@ -123,15 +122,15 @@ class MarkdownEditor extends React.Component {
   handleCheckboxClick (e) {
     e.preventDefault()
     e.stopPropagation()
-    let idMatch = /checkbox-([0-9]+)/
-    let checkedMatch = /\[x\]/i
-    let uncheckedMatch = /\[ \]/
+    const idMatch = /checkbox-([0-9]+)/
+    const checkedMatch = /\[x\]/i
+    const uncheckedMatch = /\[ \]/
     if (idMatch.test(e.target.getAttribute('id'))) {
-      let lineIndex = parseInt(e.target.getAttribute('id').match(idMatch)[1], 10) - 1
-      let lines = this.refs.code.value
+      const lineIndex = parseInt(e.target.getAttribute('id').match(idMatch)[1], 10) - 1
+      const lines = this.refs.code.value
         .split('\n')
 
-      let targetLine = lines[lineIndex]
+      const targetLine = lines[lineIndex]
 
       if (targetLine.match(checkedMatch)) {
         lines[lineIndex] = targetLine.replace(checkedMatch, '[ ]')
@@ -163,12 +162,12 @@ class MarkdownEditor extends React.Component {
   }
 
   handleKeyDown (e) {
-    let { config } = this.props
+    const { config } = this.props
     if (this.state.status !== 'CODE') return false
     const keyPressed = this.state.keyPressed
     keyPressed.add(e.keyCode)
     this.setState({ keyPressed })
-    let isNoteHandlerKey = (el) => { return keyPressed.has(el) }
+    const isNoteHandlerKey = (el) => { return keyPressed.has(el) }
     // These conditions are for ctrl-e and ctrl-w
     if (keyPressed.size === this.escapeFromEditor.length &&
         !this.state.isLocked && this.state.status === 'CODE' &&
@@ -207,14 +206,14 @@ class MarkdownEditor extends React.Component {
   }
 
   render () {
-    let { className, value, config, storageKey } = this.props
+    const { className, value, config, storageKey } = this.props
 
     let editorFontSize = parseInt(config.editor.fontSize, 10)
     if (!(editorFontSize > 0 && editorFontSize < 101)) editorFontSize = 14
     let editorIndentSize = parseInt(config.editor.indentSize, 10)
     if (!(editorFontSize > 0 && editorFontSize < 132)) editorIndentSize = 4
 
-    let previewStyle = {}
+    const previewStyle = {}
     if (this.props.ignorePreviewPointerEvents) previewStyle.pointerEvents = 'none'
 
     const storage = findStorage(storageKey)
diff --git a/browser/components/MarkdownPreview.js b/browser/components/MarkdownPreview.js
index 9ce1fcd6..959d9339 100644
--- a/browser/components/MarkdownPreview.js
+++ b/browser/components/MarkdownPreview.js
@@ -126,10 +126,10 @@ export default class MarkdownPreview extends React.Component {
     e.preventDefault()
     e.stopPropagation()
 
-    let anchor = e.target.closest('a')
-    let href = anchor.getAttribute('href')
+    const anchor = e.target.closest('a')
+    const href = anchor.getAttribute('href')
     if (_.isString(href) && href.match(/^#/)) {
-      let targetElement = this.refs.root.contentWindow.document.getElementById(href.substring(1, href.length))
+      const targetElement = this.refs.root.contentWindow.document.getElementById(href.substring(1, href.length))
       if (targetElement != null) {
         this.getWindow().scrollTo(0, targetElement.offsetTop)
       }
@@ -251,7 +251,8 @@ export default class MarkdownPreview extends React.Component {
   }
 
   applyStyle () {
-    let { fontFamily, fontSize, codeBlockFontFamily, lineNumber, codeBlockTheme } = this.props
+    const { fontSize, lineNumber, codeBlockTheme } = this.props
+    let { fontFamily, codeBlockFontFamily } = this.props
     fontFamily = _.isString(fontFamily) && fontFamily.trim().length > 0
       ? [fontFamily].concat(defaultFontFamily)
       : defaultFontFamily
@@ -284,7 +285,8 @@ export default class MarkdownPreview extends React.Component {
       el.removeEventListener('click', this.linkClickHandler)
     })
 
-    let { value, theme, indentSize, codeBlockTheme, showCopyNotification, storagePath } = this.props
+    const { theme, indentSize, showCopyNotification, storagePath } = this.props
+    let { value, codeBlockTheme } = this.props
 
     this.refs.root.contentWindow.document.body.setAttribute('data-theme', theme)
 
@@ -327,7 +329,7 @@ export default class MarkdownPreview extends React.Component {
       let syntax = CodeMirror.findModeByName(el.className)
       if (syntax == null) syntax = CodeMirror.findModeByName('Plain Text')
       CodeMirror.requireMode(syntax.mode, () => {
-        let content = htmlTextHelper.decodeEntities(el.innerHTML)
+        const content = htmlTextHelper.decodeEntities(el.innerHTML)
         const copyIcon = document.createElement('i')
         copyIcon.innerHTML = '<button class="clipboardButton"><svg width="13" height="13" viewBox="0 0 1792 1792" ><path d="M768 1664h896v-640h-416q-40 0-68-28t-28-68v-416h-384v1152zm256-1440v-64q0-13-9.5-22.5t-22.5-9.5h-704q-13 0-22.5 9.5t-9.5 22.5v64q0 13 9.5 22.5t22.5 9.5h704q13 0 22.5-9.5t9.5-22.5zm256 672h299l-299-299v299zm512 128v672q0 40-28 68t-68 28h-960q-40 0-68-28t-28-68v-160h-544q-40 0-68-28t-28-68v-1344q0-40 28-68t68-28h1088q40 0 68 28t28 68v328q21 13 36 28l408 408q28 28 48 76t20 88z"/></svg></button>'
         copyIcon.onclick = (e) => {
@@ -352,7 +354,7 @@ export default class MarkdownPreview extends React.Component {
         })
       })
     })
-    let opts = {}
+    const opts = {}
     // if (this.props.theme === 'dark') {
     //   opts['font-color'] = '#DDD'
     //   opts['line-color'] = '#DDD'
@@ -362,7 +364,7 @@ export default class MarkdownPreview extends React.Component {
     _.forEach(this.refs.root.contentWindow.document.querySelectorAll('.flowchart'), (el) => {
       Raphael.setWindow(this.getWindow())
       try {
-        let diagram = flowchart.parse(htmlTextHelper.decodeEntities(el.innerHTML))
+        const diagram = flowchart.parse(htmlTextHelper.decodeEntities(el.innerHTML))
         el.innerHTML = ''
         diagram.drawSVG(el, opts)
         _.forEach(el.querySelectorAll('a'), (el) => {
@@ -378,7 +380,7 @@ export default class MarkdownPreview extends React.Component {
     _.forEach(this.refs.root.contentWindow.document.querySelectorAll('.sequence'), (el) => {
       Raphael.setWindow(this.getWindow())
       try {
-        let diagram = SequenceDiagram.parse(htmlTextHelper.decodeEntities(el.innerHTML))
+        const diagram = SequenceDiagram.parse(htmlTextHelper.decodeEntities(el.innerHTML))
         el.innerHTML = ''
         diagram.drawSVG(el, {theme: 'simple'})
         _.forEach(el.querySelectorAll('a'), (el) => {
@@ -401,11 +403,11 @@ export default class MarkdownPreview extends React.Component {
   }
 
   scrollTo (targetRow) {
-    let blocks = this.getWindow().document.querySelectorAll('body>[data-line]')
+    const blocks = this.getWindow().document.querySelectorAll('body>[data-line]')
 
     for (let index = 0; index < blocks.length; index++) {
       let block = blocks[index]
-      let row = parseInt(block.getAttribute('data-line'))
+      const row = parseInt(block.getAttribute('data-line'))
       if (row > targetRow || index === blocks.length - 1) {
         block = blocks[index - 1]
         block != null && this.getWindow().scrollTo(0, block.offsetTop)
@@ -435,7 +437,7 @@ export default class MarkdownPreview extends React.Component {
   }
 
   render () {
-    let { className, style, tabIndex } = this.props
+    const { className, style, tabIndex } = this.props
     return (
       <iframe className={className != null
           ? 'MarkdownPreview ' + className
diff --git a/browser/components/RealtimeNotification.js b/browser/components/RealtimeNotification.js
index 6904b362..39e134b4 100644
--- a/browser/components/RealtimeNotification.js
+++ b/browser/components/RealtimeNotification.js
@@ -1,4 +1,4 @@
-import React, { PropTypes } from 'react'
+import React from 'react'
 import CSSModules from 'browser/lib/CSSModules'
 import styles from './RealtimeNotification.styl'
 
diff --git a/browser/components/SnippetTab.js b/browser/components/SnippetTab.js
index 5c0377bd..5423f3ed 100644
--- a/browser/components/SnippetTab.js
+++ b/browser/components/SnippetTab.js
@@ -86,7 +86,7 @@ class SnippetTab extends React.Component {
   }
 
   render () {
-    let { isActive, snippet, isDeletable } = this.props
+    const { isActive, snippet, isDeletable } = this.props
     return (
       <div styleName={isActive
           ? 'root--active'
diff --git a/browser/finder/NoteDetail.js b/browser/finder/NoteDetail.js
index 6fda851e..9d2f8da4 100644
--- a/browser/finder/NoteDetail.js
+++ b/browser/finder/NoteDetail.js
@@ -56,7 +56,7 @@ class NoteDetail extends React.Component {
   }
 
   selectPriorSnippet () {
-    let { note } = this.props
+    const { note } = this.props
     if (note.type === 'SNIPPET_NOTE' && note.snippets.length > 1) {
       this.setState({
         snippetIndex: (this.state.snippetIndex + note.snippets.length - 1) % note.snippets.length
@@ -65,7 +65,7 @@ class NoteDetail extends React.Component {
   }
 
   selectNextSnippet () {
-    let { note } = this.props
+    const { note } = this.props
     if (note.type === 'SNIPPET_NOTE' && note.snippets.length > 1) {
       this.setState({
         snippetIndex: (this.state.snippetIndex + 1) % note.snippets.length
@@ -74,7 +74,7 @@ class NoteDetail extends React.Component {
   }
 
   saveToClipboard () {
-    let { note } = this.props
+    const { note } = this.props
 
     if (note.type === 'MARKDOWN_NOTE') {
       clipboard.writeText(note.content)
@@ -95,7 +95,7 @@ class NoteDetail extends React.Component {
   }
 
   render () {
-    let { note, config } = this.props
+    const { note, config } = this.props
     if (note == null) {
       return (
         <div styleName='root' />
@@ -110,8 +110,8 @@ class NoteDetail extends React.Component {
     const storage = findStorage(note.storage)
 
     if (note.type === 'SNIPPET_NOTE') {
-      let tabList = note.snippets.map((snippet, index) => {
-        let isActive = this.state.snippetIndex === index
+      const tabList = note.snippets.map((snippet, index) => {
+        const isActive = this.state.snippetIndex === index
         return <div styleName={isActive
             ? 'tabList-item--active'
             : 'tabList-item'
@@ -131,8 +131,8 @@ class NoteDetail extends React.Component {
         </div>
       })
 
-      let viewList = note.snippets.map((snippet, index) => {
-        let isActive = this.state.snippetIndex === index
+      const viewList = note.snippets.map((snippet, index) => {
+        const isActive = this.state.snippetIndex === index
 
         let syntax = CodeMirror.findModeByName(pass(snippet.mode))
         if (syntax == null) syntax = CodeMirror.findModeByName('Plain Text')
diff --git a/browser/finder/NoteList.js b/browser/finder/NoteList.js
index b82c3226..17af8cf8 100644
--- a/browser/finder/NoteList.js
+++ b/browser/finder/NoteList.js
@@ -18,18 +18,18 @@ class NoteList extends React.Component {
   }
 
   componentDidUpdate () {
-    let { index } = this.props
+    const { index } = this.props
 
     if (index > -1) {
-      let list = this.refs.root
-      let item = list.childNodes[index]
+      const list = this.refs.root
+      const item = list.childNodes[index]
       if (item == null) return null
 
-      let overflowBelow = item.offsetTop + item.clientHeight - list.clientHeight - list.scrollTop > 0
+      const overflowBelow = item.offsetTop + item.clientHeight - list.clientHeight - list.scrollTop > 0
       if (overflowBelow) {
         list.scrollTop = item.offsetTop + item.clientHeight - list.clientHeight
       }
-      let overflowAbove = list.scrollTop > item.offsetTop
+      const overflowAbove = list.scrollTop > item.offsetTop
       if (overflowAbove) {
         list.scrollTop = item.offsetTop
       }
@@ -44,7 +44,7 @@ class NoteList extends React.Component {
   }
 
   handleScroll (e) {
-    let { notes } = this.props
+    const { notes } = this.props
 
     if (e.target.offsetHeight + e.target.scrollTop > e.target.scrollHeight - 100 && notes.length > this.state.range * 10 + 10) {
       this.setState({
@@ -54,9 +54,9 @@ class NoteList extends React.Component {
   }
 
   render () {
-    let { notes, index } = this.props
+    const { notes, index } = this.props
 
-    let notesList = notes
+    const notesList = notes
       .slice(0, 10 + 10 * this.state.range)
       .map((note, _index) => {
         const isActive = (index === _index)
diff --git a/browser/finder/StorageSection.js b/browser/finder/StorageSection.js
index 1c3cc95f..e775743e 100644
--- a/browser/finder/StorageSection.js
+++ b/browser/finder/StorageSection.js
@@ -19,18 +19,18 @@ class StorageSection extends React.Component {
   }
 
   handleHeaderClick (e) {
-    let { storage } = this.props
+    const { storage } = this.props
     this.props.handleStorageButtonClick(e, storage.key)
   }
 
   handleFolderClick (e, folder) {
-    let { storage } = this.props
+    const { storage } = this.props
     this.props.handleFolderButtonClick(e, storage.key, folder.key)
   }
 
   render () {
-    let { storage, filter } = this.props
-    let folderList = storage.folders
+    const { storage, filter } = this.props
+    const folderList = storage.folders
       .map(folder => (
         <StorageItem
           key={folder.key}
diff --git a/browser/finder/index.js b/browser/finder/index.js
index 15344c3d..fa582cff 100644
--- a/browser/finder/index.js
+++ b/browser/finder/index.js
@@ -2,7 +2,6 @@ import React, { PropTypes } from 'react'
 import ReactDOM from 'react-dom'
 import { connect, Provider } from 'react-redux'
 import _ from 'lodash'
-import ipc from './ipcClient'
 import store from './store'
 import CSSModules from 'browser/lib/CSSModules'
 import styles from './FinderMain.styl'
@@ -19,7 +18,7 @@ const { remote } = electron
 const { Menu } = remote
 
 function hideFinder () {
-  let finderWindow = remote.getCurrentWindow()
+  const finderWindow = remote.getCurrentWindow()
   if (global.process.platform === 'win32') {
     finderWindow.blur()
     finderWindow.hide()
@@ -136,7 +135,7 @@ class FinderMain extends React.Component {
   }
 
   handleOnlySnippetCheckboxChange (e) {
-    let { filter } = this.state
+    const { filter } = this.state
     filter.includeSnippet = e.target.checked
     this.setState({
       filter: filter,
@@ -147,7 +146,7 @@ class FinderMain extends React.Component {
   }
 
   handleOnlyMarkdownCheckboxChange (e) {
-    let { filter } = this.state
+    const { filter } = this.state
     filter.includeMarkdown = e.target.checked
     this.refs.list.resetScroll()
     this.setState({
@@ -159,7 +158,7 @@ class FinderMain extends React.Component {
   }
 
   handleAllNotesButtonClick (e) {
-    let { filter } = this.state
+    const { filter } = this.state
     filter.type = 'ALL'
     this.refs.list.resetScroll()
     this.setState({
@@ -171,7 +170,7 @@ class FinderMain extends React.Component {
   }
 
   handleStarredButtonClick (e) {
-    let { filter } = this.state
+    const { filter } = this.state
     filter.type = 'STARRED'
     this.refs.list.resetScroll()
     this.setState({
@@ -183,7 +182,7 @@ class FinderMain extends React.Component {
   }
 
   handleStorageButtonClick (e, storage) {
-    let { filter } = this.state
+    const { filter } = this.state
     filter.type = 'STORAGE'
     filter.storage = storage
     this.refs.list.resetScroll()
@@ -196,7 +195,7 @@ class FinderMain extends React.Component {
   }
 
   handleFolderButtonClick (e, storage, folder) {
-    let { filter } = this.state
+    const { filter } = this.state
     filter.type = 'FOLDER'
     filter.storage = storage
     filter.folder = folder
@@ -218,12 +217,12 @@ class FinderMain extends React.Component {
   }
 
   render () {
-    let { data, config } = this.props
-    let { filter, search } = this.state
-    let storageList = []
-    for (let key in data.storageMap) {
-      let storage = data.storageMap[key]
-      let item = (
+    const { data, config } = this.props
+    const { filter, search } = this.state
+    const storageList = []
+    for (const key in data.storageMap) {
+      const storage = data.storageMap[key]
+      const item = (
         <StorageSection
           filter={filter}
           storage={storage}
@@ -252,7 +251,7 @@ class FinderMain extends React.Component {
         notes.push(data.noteMap[id])
       })
     } else {
-      for (let key in data.noteMap) {
+      for (const key in data.noteMap) {
         notes.push(data.noteMap[key])
       }
     }
@@ -264,13 +263,13 @@ class FinderMain extends React.Component {
     }
 
     if (search.trim().length > 0) {
-      let needle = new RegExp(_.escapeRegExp(search.trim()), 'i')
+      const needle = new RegExp(_.escapeRegExp(search.trim()), 'i')
       notes = notes.filter((note) => note.title.match(needle))
     }
     notes = notes
       .sort((a, b) => new Date(b.updatedAt) - new Date(a.updatedAt))
 
-    let activeNote = notes[this.state.index]
+    const activeNote = notes[this.state.index]
     this.noteCount = notes.length
 
     return (
diff --git a/browser/finder/ipcClient.js b/browser/finder/ipcClient.js
index d35b21f2..d87bc6a3 100644
--- a/browser/finder/ipcClient.js
+++ b/browser/finder/ipcClient.js
@@ -10,7 +10,7 @@ nodeIpc.config.retry = 1500
 nodeIpc.config.silent = true
 
 function killFinder () {
-  let finderWindow = remote.getCurrentWindow()
+  const finderWindow = remote.getCurrentWindow()
   finderWindow.removeAllListeners()
   if (global.process.platform === 'darwin') {
     // Only OSX has another app process.
@@ -21,7 +21,7 @@ function killFinder () {
 }
 
 function toggleFinder () {
-  let finderWindow = remote.getCurrentWindow()
+  const finderWindow = remote.getCurrentWindow()
   if (global.process.platform === 'darwin') {
     if (finderWindow.isVisible()) {
       finderWindow.hide()
diff --git a/browser/finder/store.js b/browser/finder/store.js
index b1a70076..ca108e6b 100644
--- a/browser/finder/store.js
+++ b/browser/finder/store.js
@@ -2,7 +2,7 @@ import { combineReducers, createStore } from 'redux'
 import { routerReducer } from 'react-router-redux'
 import { DEFAULT_CONFIG } from 'browser/main/lib/ConfigManager'
 
-let defaultData = {
+const defaultData = {
   storageMap: {},
   noteMap: {},
   starredSet: [],
@@ -40,12 +40,12 @@ function config (state = DEFAULT_CONFIG, action) {
   return state
 }
 
-let reducer = combineReducers({
+const reducer = combineReducers({
   data,
   config,
   routing: routerReducer
 })
 
-let store = createStore(reducer)
+const store = createStore(reducer)
 
 export default store
diff --git a/browser/lib/Mutable.js b/browser/lib/Mutable.js
index 1f514fb2..0ae2d9cf 100644
--- a/browser/lib/Mutable.js
+++ b/browser/lib/Mutable.js
@@ -38,15 +38,15 @@ class MutableMap {
   }
 
   map (cb) {
-    let result = []
-    for (let [key, value] of this._map) {
+    const result = []
+    for (const [key, value] of this._map) {
       result.push(cb(value, key))
     }
     return result
   }
 
   toJS () {
-    let result = {}
+    const result = {}
     for (let [key, value] of this._map) {
       if (value instanceof MutableSet || value instanceof MutableMap) {
         value = value.toJS()
@@ -85,7 +85,7 @@ class MutableSet {
   }
 
   map (cb) {
-    let result = []
+    const result = []
     this._set.forEach(function (value, key) {
       result.push(cb(value, key))
     })
diff --git a/browser/lib/findNoteTitle.js b/browser/lib/findNoteTitle.js
index 46238caf..81c9400f 100644
--- a/browser/lib/findNoteTitle.js
+++ b/browser/lib/findNoteTitle.js
@@ -1,11 +1,11 @@
 export function findNoteTitle (value) {
-  let splitted = value.split('\n')
+  const splitted = value.split('\n')
   let title = null
   let isInsideCodeBlock = false
 
   splitted.some((line, index) => {
-    let trimmedLine = line.trim()
-    let trimmedNextLine = splitted[index + 1] === undefined ? '' : splitted[index + 1].trim()
+    const trimmedLine = line.trim()
+    const trimmedNextLine = splitted[index + 1] === undefined ? '' : splitted[index + 1].trim()
     if (trimmedLine.match('```')) {
       isInsideCodeBlock = !isInsideCodeBlock
     }
diff --git a/browser/lib/getTodoStatus.js b/browser/lib/getTodoStatus.js
index d65e4946..dc3deb8a 100644
--- a/browser/lib/getTodoStatus.js
+++ b/browser/lib/getTodoStatus.js
@@ -1,10 +1,10 @@
 export function getTodoStatus (content) {
-  let splitted = content.split('\n')
+  const splitted = content.split('\n')
   let numberOfTodo = 0
   let numberOfCompletedTodo = 0
 
   splitted.forEach((line) => {
-    let trimmedLine = line.trim()
+    const trimmedLine = line.trim()
     if (trimmedLine.match(/^[\+\-\*] \[\s|x\] ./)) {
       numberOfTodo++
     }
diff --git a/browser/lib/markdown.js b/browser/lib/markdown.js
index 91a04a2a..fca0259d 100644
--- a/browser/lib/markdown.js
+++ b/browser/lib/markdown.js
@@ -7,8 +7,8 @@ import _ from 'lodash'
 const katex = window.katex
 
 function createGutter (str) {
-  let lc = (str.match(/\n/g) || []).length
-  let lines = []
+  const lc = (str.match(/\n/g) || []).length
+  const lines = []
   for (let i = 1; i <= lc; i++) {
     lines.push('<span class="CodeMirror-linenumber">' + i + '</span>')
   }
@@ -76,8 +76,8 @@ md.use(require('markdown-it-plantuml'))
 md.block.ruler.at('paragraph', function (state, startLine/*, endLine */) {
   let content, terminate, i, l, token
   let nextLine = startLine + 1
-  let terminatorRules = state.md.block.ruler.getRules('paragraph')
-  let endLine = state.lineMax
+  const terminatorRules = state.md.block.ruler.getRules('paragraph')
+  const endLine = state.lineMax
 
   // jump line-by-line until empty one or EOF
   for (; nextLine < endLine && !state.isEmpty(nextLine); nextLine++) {
@@ -107,7 +107,7 @@ md.block.ruler.at('paragraph', function (state, startLine/*, endLine */) {
   token.map = [ startLine, state.line ]
 
   if (state.parentType === 'list') {
-    let match = content.match(/^\[( |x)\] ?(.+)/i)
+    const match = content.match(/^\[( |x)\] ?(.+)/i)
     if (match) {
       content = `<label class='taskListItem' for='checkbox-${startLine + 1}'><input type='checkbox'${match[1] !== ' ' ? ' checked' : ''} id='checkbox-${startLine + 1}'/> ${content.substring(4, content.length)}</label>`
     }
@@ -124,7 +124,7 @@ md.block.ruler.at('paragraph', function (state, startLine/*, endLine */) {
 })
 
 // Add line number attribute for scrolling
-let originalRender = md.renderer.render
+const originalRender = md.renderer.render
 md.renderer.render = function render (tokens, options, env) {
   tokens.forEach((token) => {
     switch (token.type) {
@@ -135,7 +135,7 @@ md.renderer.render = function render (tokens, options, env) {
         token.attrPush(['data-line', token.map[0]])
     }
   })
-  let result = originalRender.call(md.renderer, tokens, options, env)
+  const result = originalRender.call(md.renderer, tokens, options, env)
   return result
 }
 // FIXME We should not depend on global variable.
diff --git a/browser/lib/search.js b/browser/lib/search.js
index d102e381..dadc9a29 100644
--- a/browser/lib/search.js
+++ b/browser/lib/search.js
@@ -16,7 +16,7 @@ export default function searchFromNotes (notes, search) {
 
 function findByTag (notes, block) {
   const tag = block.match(/#(.+)/)[1]
-  let regExp = new RegExp(_.escapeRegExp(tag), 'i')
+  const regExp = new RegExp(_.escapeRegExp(tag), 'i')
   return notes.filter((note) => {
     if (!_.isArray(note.tags)) return false
     return note.tags.some((_tag) => {
@@ -26,7 +26,7 @@ function findByTag (notes, block) {
 }
 
 function findByWord (notes, block) {
-  let regExp = new RegExp(_.escapeRegExp(block), 'i')
+  const regExp = new RegExp(_.escapeRegExp(block), 'i')
   return notes.filter((note) => {
     if (_.isArray(note.tags) && note.tags.some((_tag) => {
       return _tag.match(regExp)
diff --git a/browser/main/Detail/FolderSelect.js b/browser/main/Detail/FolderSelect.js
index 49f84098..9aa34e5d 100644
--- a/browser/main/Detail/FolderSelect.js
+++ b/browser/main/Detail/FolderSelect.js
@@ -73,8 +73,8 @@ class FolderSelect extends React.Component {
       case 9:
         if (e.shiftKey) {
           e.preventDefault()
-          let tabbable = document.querySelectorAll('a:not([disabled]), button:not([disabled]), input[type=text]:not([disabled]), [tabindex]:not([disabled]):not([tabindex="-1"])')
-          let previousEl = tabbable[Array.prototype.indexOf.call(tabbable, this.refs.root) - 1]
+          const tabbable = document.querySelectorAll('a:not([disabled]), button:not([disabled]), input[type=text]:not([disabled]), [tabindex]:not([disabled]):not([tabindex="-1"])')
+          const previousEl = tabbable[Array.prototype.indexOf.call(tabbable, this.refs.root) - 1]
           if (previousEl != null) previousEl.focus()
         }
     }
@@ -89,9 +89,9 @@ class FolderSelect extends React.Component {
   }
 
   handleSearchInputChange (e) {
-    let { folders } = this.props
-    let search = this.refs.search.value
-    let optionIndex = search.length > 0
+    const { folders } = this.props
+    const search = this.refs.search.value
+    const optionIndex = search.length > 0
       ? _.findIndex(folders, (folder) => {
         return folder.name.match(new RegExp('^' + _.escapeRegExp(search), 'i'))
       })
@@ -129,7 +129,7 @@ class FolderSelect extends React.Component {
 
   nextOption () {
     let { optionIndex } = this.state
-    let { folders } = this.props
+    const { folders } = this.props
 
     optionIndex++
     if (optionIndex >= folders.length) optionIndex = 0
@@ -140,7 +140,7 @@ class FolderSelect extends React.Component {
   }
 
   previousOption () {
-    let { folders } = this.props
+    const { folders } = this.props
     let { optionIndex } = this.state
 
     optionIndex--
@@ -152,10 +152,10 @@ class FolderSelect extends React.Component {
   }
 
   selectOption () {
-    let { folders } = this.props
-    let optionIndex = this.state.optionIndex
+    const { folders } = this.props
+    const optionIndex = this.state.optionIndex
 
-    let folder = folders[optionIndex]
+    const folder = folders[optionIndex]
     if (folder != null) {
       this.setState({
         status: 'FOCUS'
@@ -184,10 +184,10 @@ class FolderSelect extends React.Component {
   }
 
   render () {
-    let { className, data, value } = this.props
-    let splitted = value.split('-')
-    let storageKey = splitted.shift()
-    let folderKey = splitted.shift()
+    const { className, data, value } = this.props
+    const splitted = value.split('-')
+    const storageKey = splitted.shift()
+    const folderKey = splitted.shift()
     let options = []
     data.storageMap.forEach((storage, index) => {
       storage.folders.forEach((folder) => {
@@ -198,14 +198,14 @@ class FolderSelect extends React.Component {
       })
     })
 
-    let currentOption = options.filter((option) => option.storage.key === storageKey && option.folder.key === folderKey)[0]
+    const currentOption = options.filter((option) => option.storage.key === storageKey && option.folder.key === folderKey)[0]
 
     if (this.state.search.trim().length > 0) {
-      let filter = new RegExp('^' + _.escapeRegExp(this.state.search), 'i')
+      const filter = new RegExp('^' + _.escapeRegExp(this.state.search), 'i')
       options = options.filter((option) => filter.test(option.folder.name))
     }
 
-    let optionList = options
+    const optionList = options
       .map((option, index) => {
         return (
           <div styleName={index === this.state.optionIndex
diff --git a/browser/main/Detail/MarkdownNoteDetail.js b/browser/main/Detail/MarkdownNoteDetail.js
index d3d72be8..e84a94e8 100644
--- a/browser/main/Detail/MarkdownNoteDetail.js
+++ b/browser/main/Detail/MarkdownNoteDetail.js
@@ -25,7 +25,7 @@ import striptags from 'striptags'
 
 const electron = require('electron')
 const { remote } = electron
-const { Menu, MenuItem, dialog } = remote
+const { dialog } = remote
 
 class MarkdownNoteDetail extends React.Component {
   constructor (props) {
@@ -74,7 +74,7 @@ class MarkdownNoteDetail extends React.Component {
   }
 
   handleChange (e) {
-    let { note } = this.state
+    const { note } = this.state
 
     note.content = this.refs.content.value
     if (this.refs.tags) note.tags = this.refs.tags.value
@@ -96,7 +96,7 @@ class MarkdownNoteDetail extends React.Component {
   }
 
   saveNow () {
-    let { note, dispatch } = this.props
+    const { note, dispatch } = this.props
     clearTimeout(this.saveQueue)
     this.saveQueue = null
 
@@ -112,11 +112,11 @@ class MarkdownNoteDetail extends React.Component {
   }
 
   handleFolderChange (e) {
-    let { note } = this.state
-    let value = this.refs.folder.value
-    let splitted = value.split('-')
-    let newStorageKey = splitted.shift()
-    let newFolderKey = splitted.shift()
+    const { note } = this.state
+    const value = this.refs.folder.value
+    const splitted = value.split('-')
+    const newStorageKey = splitted.shift()
+    const newFolderKey = splitted.shift()
 
     dataApi
       .moveNote(note.storage, note.key, newStorageKey, newFolderKey)
@@ -125,7 +125,7 @@ class MarkdownNoteDetail extends React.Component {
           isMovingNote: true,
           note: Object.assign({}, newNote)
         }, () => {
-          let { dispatch, location } = this.props
+          const { dispatch, location } = this.props
           dispatch({
             type: 'MOVE_NOTE',
             originNote: note,
@@ -145,7 +145,7 @@ class MarkdownNoteDetail extends React.Component {
   }
 
   handleStarButtonClick (e) {
-    let { note } = this.state
+    const { note } = this.state
     if (!note.isStarred) AwsMobileAnalyticsConfig.recordDynamicCustomEvent('ADD_STAR')
 
     note.isStarred = !note.isStarred
@@ -170,22 +170,22 @@ class MarkdownNoteDetail extends React.Component {
   }
 
   handleTrashButtonClick (e) {
-    let { note } = this.state
+    const { note } = this.state
     const { isTrashed } = note
 
     if (isTrashed) {
-      let dialogueButtonIndex = dialog.showMessageBox(remote.getCurrentWindow(), {
+      const dialogueButtonIndex = dialog.showMessageBox(remote.getCurrentWindow(), {
         type: 'warning',
         message: 'Confirm note deletion',
         detail: 'This will permanently remove this note.',
         buttons: ['Confirm', 'Cancel']
       })
       if (dialogueButtonIndex === 1) return
-      let { note, dispatch } = this.props
+      const { note, dispatch } = this.props
       dataApi
         .deleteNote(note.storage, note.key)
         .then((data) => {
-          let dispatchHandler = () => {
+          const dispatchHandler = () => {
             dispatch({
               type: 'DELETE_NOTE',
               storageKey: data.storageKey,
@@ -207,7 +207,7 @@ class MarkdownNoteDetail extends React.Component {
   }
 
   handleUndoButtonClick (e) {
-    let { note } = this.state
+    const { note } = this.state
 
     note.isTrashed = false
 
@@ -262,12 +262,12 @@ class MarkdownNoteDetail extends React.Component {
   }
 
   render () {
-    let { data, config, location } = this.props
-    let { note } = this.state
-    let storageKey = note.storage
-    let folderKey = note.folder
+    const { data, config, location } = this.props
+    const { note } = this.state
+    const storageKey = note.storage
+    const folderKey = note.folder
 
-    let options = []
+    const options = []
     data.storageMap.forEach((storage, index) => {
       storage.folders.forEach((folder) => {
         options.push({
@@ -276,7 +276,7 @@ class MarkdownNoteDetail extends React.Component {
         })
       })
     })
-    let currentOption = options.filter((option) => option.storage.key === storageKey && option.folder.key === folderKey)[0]
+    const currentOption = options.filter((option) => option.storage.key === storageKey && option.folder.key === folderKey)[0]
 
     const trashTopBar = <div styleName='info'>
       <div styleName='info-left'>
diff --git a/browser/main/Detail/SnippetNoteDetail.js b/browser/main/Detail/SnippetNoteDetail.js
index 839f8a24..c48a178b 100644
--- a/browser/main/Detail/SnippetNoteDetail.js
+++ b/browser/main/Detail/SnippetNoteDetail.js
@@ -61,7 +61,7 @@ class SnippetNoteDetail extends React.Component {
   componentWillReceiveProps (nextProps) {
     if (nextProps.note.key !== this.props.note.key && !this.isMovingNote) {
       if (this.saveQueue != null) this.saveNow()
-      let nextNote = Object.assign({
+      const nextNote = Object.assign({
         description: ''
       }, nextProps.note, {
         snippets: nextProps.note.snippets.map((snippet) => Object.assign({}, snippet))
@@ -70,7 +70,7 @@ class SnippetNoteDetail extends React.Component {
         snippetIndex: 0,
         note: nextNote
       }, () => {
-        let { snippets } = this.state.note
+        const { snippets } = this.state.note
         snippets.forEach((snippet, index) => {
           this.refs['code-' + index].reload()
         })
@@ -84,7 +84,7 @@ class SnippetNoteDetail extends React.Component {
   }
 
   handleChange (e) {
-    let { note } = this.state
+    const { note } = this.state
 
     if (this.refs.tags) note.tags = this.refs.tags.value
     note.description = this.refs.description.value
@@ -106,7 +106,7 @@ class SnippetNoteDetail extends React.Component {
   }
 
   saveNow () {
-    let { note, dispatch } = this.props
+    const { note, dispatch } = this.props
     clearTimeout(this.saveQueue)
     this.saveQueue = null
 
@@ -122,11 +122,11 @@ class SnippetNoteDetail extends React.Component {
   }
 
   handleFolderChange (e) {
-    let { note } = this.state
-    let value = this.refs.folder.value
-    let splitted = value.split('-')
-    let newStorageKey = splitted.shift()
-    let newFolderKey = splitted.shift()
+    const { note } = this.state
+    const value = this.refs.folder.value
+    const splitted = value.split('-')
+    const newStorageKey = splitted.shift()
+    const newFolderKey = splitted.shift()
 
     dataApi
       .moveNote(note.storage, note.key, newStorageKey, newFolderKey)
@@ -135,7 +135,7 @@ class SnippetNoteDetail extends React.Component {
           isMovingNote: true,
           note: Object.assign({}, newNote)
         }, () => {
-          let { dispatch, location } = this.props
+          const { dispatch, location } = this.props
           dispatch({
             type: 'MOVE_NOTE',
             originNote: note,
@@ -155,7 +155,7 @@ class SnippetNoteDetail extends React.Component {
   }
 
   handleStarButtonClick (e) {
-    let { note } = this.state
+    const { note } = this.state
     if (!note.isStarred) AwsMobileAnalyticsConfig.recordDynamicCustomEvent('ADD_STAR')
 
     note.isStarred = !note.isStarred
@@ -172,22 +172,22 @@ class SnippetNoteDetail extends React.Component {
   }
 
   handleTrashButtonClick (e) {
-    let { note } = this.state
+    const { note } = this.state
     const { isTrashed } = note
 
     if (isTrashed) {
-      let dialogueButtonIndex = dialog.showMessageBox(remote.getCurrentWindow(), {
+      const dialogueButtonIndex = dialog.showMessageBox(remote.getCurrentWindow(), {
         type: 'warning',
         message: 'Confirm note deletion',
         detail: 'This will permanently remove this note.',
         buttons: ['Confirm', 'Cancel']
       })
       if (dialogueButtonIndex === 1) return
-      let { note, dispatch } = this.props
+      const { note, dispatch } = this.props
       dataApi
         .deleteNote(note.storage, note.key)
         .then((data) => {
-          let dispatchHandler = () => {
+          const dispatchHandler = () => {
             dispatch({
               type: 'DELETE_NOTE',
               storageKey: data.storageKey,
@@ -209,7 +209,7 @@ class SnippetNoteDetail extends React.Component {
   }
 
   handleUndoButtonClick (e) {
-    let { note } = this.state
+    const { note } = this.state
 
     note.isTrashed = false
 
@@ -238,7 +238,7 @@ class SnippetNoteDetail extends React.Component {
   handleTabDeleteButtonClick (e, index) {
     if (this.state.note.snippets.length > 1) {
       if (this.state.note.snippets[index].content.trim().length > 0) {
-        let dialogIndex = dialog.showMessageBox(remote.getCurrentWindow(), {
+        const dialogIndex = dialog.showMessageBox(remote.getCurrentWindow(), {
           type: 'warning',
           message: 'Delete a snippet',
           detail: 'This work cannot be undone.',
@@ -288,7 +288,7 @@ class SnippetNoteDetail extends React.Component {
 
   handleModeOptionClick (index, name) {
     return (e) => {
-      let snippets = this.state.note.snippets.slice()
+      const snippets = this.state.note.snippets.slice()
       snippets[index].mode = name
       this.setState({note: Object.assign(this.state.note, {snippets: snippets})})
 
@@ -306,7 +306,7 @@ class SnippetNoteDetail extends React.Component {
 
   handleCodeChange (index) {
     return (e) => {
-      let snippets = this.state.note.snippets.slice()
+      const snippets = this.state.note.snippets.slice()
       snippets[index].content = this.refs['code-' + index].value
       this.setState({note: Object.assign(this.state.note, {snippets: snippets})})
       this.setState({
@@ -333,7 +333,7 @@ class SnippetNoteDetail extends React.Component {
         break
       case 76:
         {
-          let isSuper = global.process.platform === 'darwin'
+          const isSuper = global.process.platform === 'darwin'
             ? e.metaKey
             : e.ctrlKey
           if (isSuper) {
@@ -344,7 +344,7 @@ class SnippetNoteDetail extends React.Component {
         break
       case 84:
         {
-          let isSuper = global.process.platform === 'darwin'
+          const isSuper = global.process.platform === 'darwin'
             ? e.metaKey
             : e.ctrlKey
           if (isSuper) {
@@ -357,7 +357,7 @@ class SnippetNoteDetail extends React.Component {
   }
 
   handleModeButtonClick (e, index) {
-    let menu = new Menu()
+    const menu = new Menu()
     CodeMirror.modeInfo.forEach((mode) => {
       menu.append(new MenuItem({
         label: mode.name,
@@ -398,8 +398,8 @@ class SnippetNoteDetail extends React.Component {
   }
 
   handleIndentSizeItemClick (e, indentSize) {
-    let { config, dispatch } = this.props
-    let editor = Object.assign({}, config.editor, {
+    const { config, dispatch } = this.props
+    const editor = Object.assign({}, config.editor, {
       indentSize
     })
     ConfigManager.set({
@@ -414,8 +414,8 @@ class SnippetNoteDetail extends React.Component {
   }
 
   handleIndentTypeItemClick (e, indentType) {
-    let { config, dispatch } = this.props
-    let editor = Object.assign({}, config.editor, {
+    const { config, dispatch } = this.props
+    const editor = Object.assign({}, config.editor, {
       indentType
     })
     ConfigManager.set({
@@ -434,14 +434,14 @@ class SnippetNoteDetail extends React.Component {
   }
 
   addSnippet () {
-    let { note } = this.state
+    const { note } = this.state
 
     note.snippets = note.snippets.concat([{
       name: '',
       mode: 'Plain Text',
       content: ''
     }])
-    let snippetIndex = note.snippets.length - 1
+    const snippetIndex = note.snippets.length - 1
 
     this.setState({
       note,
@@ -487,19 +487,19 @@ class SnippetNoteDetail extends React.Component {
   }
 
   render () {
-    let { data, config, location } = this.props
-    let { note } = this.state
+    const { data, config, location } = this.props
+    const { note } = this.state
 
-    let storageKey = note.storage
-    let folderKey = note.folder
+    const storageKey = note.storage
+    const folderKey = note.folder
 
     let editorFontSize = parseInt(config.editor.fontSize, 10)
     if (!(editorFontSize > 0 && editorFontSize < 101)) editorFontSize = 14
     let editorIndentSize = parseInt(config.editor.indentSize, 10)
     if (!(editorFontSize > 0 && editorFontSize < 132)) editorIndentSize = 4
 
-    let tabList = note.snippets.map((snippet, index) => {
-      let isActive = this.state.snippetIndex === index
+    const tabList = note.snippets.map((snippet, index) => {
+      const isActive = this.state.snippetIndex === index
 
       return <SnippetTab
         key={index}
@@ -513,8 +513,8 @@ class SnippetNoteDetail extends React.Component {
       />
     })
 
-    let viewList = note.snippets.map((snippet, index) => {
-      let isActive = this.state.snippetIndex === index
+    const viewList = note.snippets.map((snippet, index) => {
+      const isActive = this.state.snippetIndex === index
 
       let syntax = CodeMirror.findModeByName(pass(snippet.mode))
       if (syntax == null) syntax = CodeMirror.findModeByName('Plain Text')
@@ -548,7 +548,7 @@ class SnippetNoteDetail extends React.Component {
       </div>
     })
 
-    let options = []
+    const options = []
     data.storageMap.forEach((storage, index) => {
       storage.folders.forEach((folder) => {
         options.push({
@@ -557,7 +557,7 @@ class SnippetNoteDetail extends React.Component {
         })
       })
     })
-    let currentOption = options.filter((option) => option.storage.key === storageKey && option.folder.key === folderKey)[0]
+    const currentOption = options.filter((option) => option.storage.key === storageKey && option.folder.key === folderKey)[0]
 
     const trashTopBar = <div styleName='info'>
       <div styleName='info-left'>
diff --git a/browser/main/Detail/StarButton.js b/browser/main/Detail/StarButton.js
index 7350bc98..be751589 100644
--- a/browser/main/Detail/StarButton.js
+++ b/browser/main/Detail/StarButton.js
@@ -31,7 +31,7 @@ class StarButton extends React.Component {
   }
 
   render () {
-    let { className } = this.props
+    const { className } = this.props
 
     return (
       <button className={_.isString(className)
diff --git a/browser/main/Detail/TagSelect.js b/browser/main/Detail/TagSelect.js
index d44d4ab3..df0eaddb 100644
--- a/browser/main/Detail/TagSelect.js
+++ b/browser/main/Detail/TagSelect.js
@@ -59,7 +59,7 @@ class TagSelect extends React.Component {
   submitTag () {
     AwsMobileAnalyticsConfig.recordDynamicCustomEvent('ADD_TAG')
     let { value } = this.props
-    let newTag = this.refs.newTag.value.trim().replace(/ +/g, '_')
+    const newTag = this.refs.newTag.value.trim().replace(/ +/g, '_')
 
     if (newTag.length <= 0) {
       this.setState({
@@ -101,9 +101,9 @@ class TagSelect extends React.Component {
   }
 
   render () {
-    let { value, className } = this.props
+    const { value, className } = this.props
 
-    let tagList = _.isArray(value)
+    const tagList = _.isArray(value)
       ? value.map((tag) => {
         return (
           <span styleName='tag'
diff --git a/browser/main/Detail/index.js b/browser/main/Detail/index.js
index 884c6452..afa72a8f 100644
--- a/browser/main/Detail/index.js
+++ b/browser/main/Detail/index.js
@@ -32,12 +32,12 @@ class Detail extends React.Component {
   }
 
   render () {
-    let { location, data, config } = this.props
+    const { location, data, config } = this.props
     let note = null
     if (location.query.key != null) {
-      let splitted = location.query.key.split('-')
-      let storageKey = splitted.shift()
-      let noteKey = splitted.shift()
+      const splitted = location.query.key.split('-')
+      const storageKey = splitted.shift()
+      const noteKey = splitted.shift()
 
       note = data.noteMap.get(storageKey + '-' + noteKey)
     }
diff --git a/browser/main/Main.js b/browser/main/Main.js
index a660c504..4f0e3184 100644
--- a/browser/main/Main.js
+++ b/browser/main/Main.js
@@ -23,7 +23,7 @@ class Main extends React.Component {
       mobileAnalytics.initAwsMobileAnalytics()
     }
 
-    let { config } = props
+    const { config } = props
 
     this.state = {
       isRightSliderFocused: false,
@@ -39,7 +39,7 @@ class Main extends React.Component {
   }
 
   getChildContext () {
-    let { status, config } = this.props
+    const { status, config } = this.props
 
     return {
       status,
@@ -48,7 +48,7 @@ class Main extends React.Component {
   }
 
   componentDidMount () {
-    let { dispatch, config } = this.props
+    const { dispatch, config } = this.props
 
     if (config.ui.theme === 'dark') {
       document.body.setAttribute('data-theme', 'dark')
@@ -99,8 +99,8 @@ class Main extends React.Component {
       this.setState({
         isRightSliderFocused: false
       }, () => {
-        let { dispatch } = this.props
-        let newListWidth = this.state.listWidth
+        const { dispatch } = this.props
+        const newListWidth = this.state.listWidth
         // TODO: ConfigManager should dispatch itself.
         ConfigManager.set({listWidth: newListWidth})
         dispatch({
@@ -115,8 +115,8 @@ class Main extends React.Component {
       this.setState({
         isLeftSliderFocused: false
       }, () => {
-        let { dispatch } = this.props
-        let navWidth = this.state.navWidth
+        const { dispatch } = this.props
+        const navWidth = this.state.navWidth
         // TODO: ConfigManager should dispatch itself.
         ConfigManager.set({ navWidth })
         dispatch({
@@ -129,7 +129,7 @@ class Main extends React.Component {
 
   handleMouseMove (e) {
     if (this.state.isRightSliderFocused) {
-      let offset = this.refs.body.getBoundingClientRect().left
+      const offset = this.refs.body.getBoundingClientRect().left
       let newListWidth = e.pageX - offset
       if (newListWidth < 10) {
         newListWidth = 10
@@ -182,7 +182,7 @@ class Main extends React.Component {
   }
 
   render () {
-    let { config } = this.props
+    const { config } = this.props
 
     // the width of the navigation bar when it is folded/collapsed
     const foldedNavigationWidth = 44
diff --git a/browser/main/NewNoteButton/index.js b/browser/main/NewNoteButton/index.js
index ff8227e0..0f04d060 100644
--- a/browser/main/NewNoteButton/index.js
+++ b/browser/main/NewNoteButton/index.js
@@ -4,9 +4,7 @@ import styles from './NewNoteButton.styl'
 import _ from 'lodash'
 import modal from 'browser/main/lib/modal'
 import NewNoteModal from 'browser/main/modals/NewNoteModal'
-import { hashHistory } from 'react-router'
 import eventEmitter from 'browser/main/lib/eventEmitter'
-import dataApi from 'browser/main/lib/dataApi'
 
 const { remote } = require('electron')
 const { dialog } = remote
@@ -34,7 +32,7 @@ class NewNoteButton extends React.Component {
   }
 
   handleNewNoteButtonClick (e) {
-    const { config, location, dispatch } = this.props
+    const { location, dispatch } = this.props
     const { storage, folder } = this.resolveTargetFolder()
 
     modal.open(NewNoteModal, {
@@ -51,7 +49,7 @@ class NewNoteButton extends React.Component {
 
     // Find first storage
     if (storage == null) {
-      for (let kv of data.storageMap) {
+      for (const kv of data.storageMap) {
         storage = kv[1]
         break
       }
diff --git a/browser/main/NoteList/index.js b/browser/main/NoteList/index.js
index f0ffec3d..df47c1c4 100644
--- a/browser/main/NoteList/index.js
+++ b/browser/main/NoteList/index.js
@@ -13,7 +13,6 @@ import fs from 'fs'
 import { hashHistory } from 'react-router'
 import markdown from 'browser/lib/markdown'
 import { findNoteTitle } from 'browser/lib/findNoteTitle'
-import stripgtags from 'striptags'
 import store from 'browser/main/store'
 
 const { remote } = require('electron')
@@ -89,10 +88,10 @@ class NoteList extends React.Component {
   }
 
   componentDidUpdate (prevProps) {
-    let { location } = this.props
+    const { location } = this.props
 
     if (this.notes.length > 0 && location.query.key == null) {
-      let { router } = this.context
+      const { router } = this.context
       if (!location.pathname.match(/\/searched/)) this.contextNotes = this.getContextNotes()
       router.replace({
         pathname: location.pathname,
@@ -107,16 +106,16 @@ class NoteList extends React.Component {
     if (_.isString(location.query.key) && prevProps.location.query.key === location.query.key) {
       const targetIndex = this.getTargetIndex()
       if (targetIndex > -1) {
-        let list = this.refs.list
-        let item = list.childNodes[targetIndex]
+        const list = this.refs.list
+        const item = list.childNodes[targetIndex]
 
         if (item == null) return false
 
-        let overflowBelow = item.offsetTop + item.clientHeight - list.clientHeight - list.scrollTop > 0
+        const overflowBelow = item.offsetTop + item.clientHeight - list.clientHeight - list.scrollTop > 0
         if (overflowBelow) {
           list.scrollTop = item.offsetTop + item.clientHeight - list.clientHeight
         }
-        let overflowAbove = list.scrollTop > item.offsetTop
+        const overflowAbove = list.scrollTop > item.offsetTop
         if (overflowAbove) {
           list.scrollTop = item.offsetTop
         }
@@ -128,8 +127,8 @@ class NoteList extends React.Component {
     if (this.notes == null || this.notes.length === 0) {
       return
     }
-    let { router } = this.context
-    let { location } = this.props
+    const { router } = this.context
+    const { location } = this.props
 
     let targetIndex = this.getTargetIndex()
 
@@ -151,8 +150,8 @@ class NoteList extends React.Component {
     if (this.notes == null || this.notes.length === 0) {
       return
     }
-    let { router } = this.context
-    let { location } = this.props
+    const { router } = this.context
+    const { location } = this.props
 
     let targetIndex = this.getTargetIndex()
 
@@ -226,8 +225,7 @@ class NoteList extends React.Component {
   }
 
   getNotes () {
-    let { data, params, location } = this.props
-    let { router } = this.context
+    const { data, params, location } = this.props
 
     if (location.pathname.match(/\/home/) || location.pathname.match(/\alltags/)) {
       const allNotes = data.noteMap.map((note) => note)
@@ -300,8 +298,8 @@ class NoteList extends React.Component {
   }
 
   handleNoteClick (e, uniqueKey) {
-    let { router } = this.context
-    let { location } = this.props
+    const { router } = this.context
+    const { location } = this.props
 
     router.push({
       pathname: location.pathname,
@@ -312,9 +310,9 @@ class NoteList extends React.Component {
   }
 
   handleSortByChange (e) {
-    let { dispatch } = this.props
+    const { dispatch } = this.props
 
-    let config = {
+    const config = {
       sortBy: e.target.value
     }
 
@@ -326,9 +324,9 @@ class NoteList extends React.Component {
   }
 
   handleListStyleButtonClick (e, style) {
-    let { dispatch } = this.props
+    const { dispatch } = this.props
 
-    let config = {
+    const config = {
       listStyle: style
     }
 
@@ -381,16 +379,9 @@ class NoteList extends React.Component {
   }
 
   pinToTop (e, uniqueKey) {
-    const { data, params } = this.props
-    const storageKey = params.storageKey
-    const folderKey = params.folderKey
-
-    const currentStorage = data.storageMap.get(storageKey)
-    const currentFolder = _.find(currentStorage.folders, {key: folderKey})
-
     this.handleNoteClick(e, uniqueKey)
     const targetIndex = this.getTargetIndex()
-    let note = this.notes[targetIndex]
+    const note = this.notes[targetIndex]
     note.isPinned = !note.isPinned
 
     dataApi
@@ -409,8 +400,6 @@ class NoteList extends React.Component {
   }
 
   importFromFile () {
-    const { dispatch, location } = this.props
-
     const options = {
       filters: [
         { name: 'Documents', extensions: ['md', 'txt'] }
@@ -475,7 +464,7 @@ class NoteList extends React.Component {
 
     // Find first storage
     if (storage == null) {
-      for (let kv of data.storageMap) {
+      for (const kv of data.storageMap) {
         storage = kv[1]
         break
       }
@@ -500,8 +489,9 @@ class NoteList extends React.Component {
   }
 
   render () {
-    let { location, notes, config, dispatch } = this.props
-    let sortFunc = config.sortBy === 'CREATED_AT'
+    const { location, config } = this.props
+    let { notes } = this.props
+    const sortFunc = config.sortBy === 'CREATED_AT'
       ? sortByCreatedAt
       : config.sortBy === 'ALPHABETICAL'
       ? sortByAlphabetical
@@ -533,7 +523,7 @@ class NoteList extends React.Component {
       }
     })
 
-    let noteList = notes
+    const noteList = notes
       .map(note => {
         if (note == null) {
           return null
diff --git a/browser/main/SideNav/StorageItem.js b/browser/main/SideNav/StorageItem.js
index 38f2924f..ac1209cf 100644
--- a/browser/main/SideNav/StorageItem.js
+++ b/browser/main/SideNav/StorageItem.js
@@ -22,7 +22,7 @@ class StorageItem extends React.Component {
   }
 
   handleHeaderContextMenu (e) {
-    let menu = new Menu()
+    const menu = new Menu()
     menu.append(new MenuItem({
       label: 'Add Folder',
       click: (e) => this.handleAddFolderButtonClick(e)
@@ -38,7 +38,7 @@ class StorageItem extends React.Component {
   }
 
   handleUnlinkStorageClick (e) {
-    let index = dialog.showMessageBox(remote.getCurrentWindow(), {
+    const index = dialog.showMessageBox(remote.getCurrentWindow(), {
       type: 'warning',
       message: 'Unlink Storage',
       detail: 'This work will just detatches a storage from Boostnote. (Any data won\'t be deleted.)',
@@ -46,7 +46,7 @@ class StorageItem extends React.Component {
     })
 
     if (index === 0) {
-      let { storage, dispatch } = this.props
+      const { storage, dispatch } = this.props
       dataApi.removeStorage(storage.key)
         .then(() => {
           dispatch({
@@ -67,7 +67,7 @@ class StorageItem extends React.Component {
   }
 
   handleAddFolderButtonClick (e) {
-    let { storage } = this.props
+    const { storage } = this.props
 
     modal.open(CreateFolderModal, {
       storage
@@ -75,19 +75,19 @@ class StorageItem extends React.Component {
   }
 
   handleHeaderInfoClick (e) {
-    let { storage } = this.props
+    const { storage } = this.props
     hashHistory.push('/storages/' + storage.key)
   }
 
   handleFolderButtonClick (folderKey) {
     return (e) => {
-      let { storage } = this.props
+      const { storage } = this.props
       hashHistory.push('/storages/' + storage.key + '/folders/' + folderKey)
     }
   }
 
   handleFolderButtonContextMenu (e, folder) {
-    let menu = new Menu()
+    const menu = new Menu()
     menu.append(new MenuItem({
       label: 'Rename Folder',
       click: (e) => this.handleRenameFolderClick(e, folder)
@@ -103,7 +103,7 @@ class StorageItem extends React.Component {
   }
 
   handleRenameFolderClick (e, folder) {
-    let { storage } = this.props
+    const { storage } = this.props
     modal.open(RenameFolderModal, {
       storage,
       folder
@@ -111,7 +111,7 @@ class StorageItem extends React.Component {
   }
 
   handleFolderDeleteClick (e, folder) {
-    let index = dialog.showMessageBox(remote.getCurrentWindow(), {
+    const index = dialog.showMessageBox(remote.getCurrentWindow(), {
       type: 'warning',
       message: 'Delete Folder',
       detail: 'This will delete all notes in the folder and can not be undone.',
@@ -119,7 +119,7 @@ class StorageItem extends React.Component {
     })
 
     if (index === 0) {
-      let { storage, dispatch } = this.props
+      const { storage, dispatch } = this.props
       dataApi
         .deleteFolder(storage.key, folder.key)
         .then((data) => {
@@ -154,7 +154,7 @@ class StorageItem extends React.Component {
        dataApi
         .deleteNote(noteData.storage, noteData.key)
         .then((data) => {
-          let dispatchHandler = () => {
+          const dispatchHandler = () => {
             dispatch({
               type: 'DELETE_NOTE',
               storageKey: data.storageKey,
@@ -179,11 +179,11 @@ class StorageItem extends React.Component {
   }
 
   render () {
-    let { storage, location, isFolded, data, dispatch } = this.props
-    let { folderNoteMap, trashedSet } = data
-    let folderList = storage.folders.map((folder) => {
-      let isActive = !!(location.pathname.match(new RegExp('\/storages\/' + storage.key + '\/folders\/' + folder.key)))
-      let noteSet = folderNoteMap.get(storage.key + '-' + folder.key)
+    const { storage, location, isFolded, data, dispatch } = this.props
+    const { folderNoteMap, trashedSet } = data
+    const folderList = storage.folders.map((folder) => {
+      const isActive = !!(location.pathname.match(new RegExp('\/storages\/' + storage.key + '\/folders\/' + folder.key)))
+      const noteSet = folderNoteMap.get(storage.key + '-' + folder.key)
 
       let noteCount = 0
       if (noteSet) {
@@ -211,7 +211,7 @@ class StorageItem extends React.Component {
       )
     })
 
-    let isActive = location.pathname.match(new RegExp('\/storages\/' + storage.key + '$'))
+    const isActive = location.pathname.match(new RegExp('\/storages\/' + storage.key + '$'))
 
     return (
       <div styleName={isFolded ? 'root--folded' : 'root'}
diff --git a/browser/main/SideNav/index.js b/browser/main/SideNav/index.js
index 30c8d3ac..41a1b93f 100644
--- a/browser/main/SideNav/index.js
+++ b/browser/main/SideNav/index.js
@@ -27,17 +27,17 @@ class SideNav extends React.Component {
   }
 
   handleHomeButtonClick (e) {
-    let { router } = this.context
+    const { router } = this.context
     router.push('/home')
   }
 
   handleStarredButtonClick (e) {
-    let { router } = this.context
+    const { router } = this.context
     router.push('/starred')
   }
 
   handleToggleButtonClick (e) {
-    let { dispatch, config } = this.props
+    const { dispatch, config } = this.props
 
     ConfigManager.set({isSideNavFolded: !config.isSideNavFolded})
     dispatch({
@@ -47,7 +47,7 @@ class SideNav extends React.Component {
   }
 
   handleTrashedButtonClick (e) {
-    let { router } = this.context
+    const { router } = this.context
     router.push('/trashed')
   }
 
@@ -62,7 +62,7 @@ class SideNav extends React.Component {
   }
 
   SideNavComponent (isFolded, storageList) {
-    let { location, data } = this.props
+    const { location, data } = this.props
 
     const isHomeActive = !!location.pathname.match(/^\/home$/)
     const isStarredActive = !!location.pathname.match(/^\/starred$/)
@@ -109,7 +109,7 @@ class SideNav extends React.Component {
 
   tagListComponent () {
     const { data, location } = this.props
-    let tagList = data.tagNoteMap.map((tag, key) => {
+    const tagList = data.tagNoteMap.map((tag, key) => {
       return key
     })
     return (
@@ -136,11 +136,11 @@ class SideNav extends React.Component {
   }
 
   render () {
-    let { data, location, config, dispatch } = this.props
+    const { data, location, config, dispatch } = this.props
 
-    let isFolded = config.isSideNavFolded
+    const isFolded = config.isSideNavFolded
 
-    let storageList = data.storageMap.map((storage, key) => {
+    const storageList = data.storageMap.map((storage, key) => {
       return <StorageItem
         key={storage.key}
         storage={storage}
@@ -150,7 +150,7 @@ class SideNav extends React.Component {
         dispatch={dispatch}
       />
     })
-    let style = {}
+    const style = {}
     if (!isFolded) style.width = this.props.width
     const isTagActive = location.pathname.match(/tag/)
     return (
diff --git a/browser/main/StatusBar/index.js b/browser/main/StatusBar/index.js
index ae044e7f..36b36bab 100644
--- a/browser/main/StatusBar/index.js
+++ b/browser/main/StatusBar/index.js
@@ -11,7 +11,7 @@ const zoomOptions = [0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2
 
 class StatusBar extends React.Component {
   updateApp () {
-    let index = dialog.showMessageBox(remote.getCurrentWindow(), {
+    const index = dialog.showMessageBox(remote.getCurrentWindow(), {
       type: 'warning',
       message: 'Update Boostnote',
       detail: 'New Boostnote is ready to be installed.',
@@ -24,7 +24,7 @@ class StatusBar extends React.Component {
   }
 
   handleZoomButtonClick (e) {
-    let menu = new Menu()
+    const menu = new Menu()
 
     zoomOptions.forEach((zoom) => {
       menu.append(new MenuItem({
@@ -37,7 +37,7 @@ class StatusBar extends React.Component {
   }
 
   handleZoomMenuItemClick (zoomFactor) {
-    let { dispatch } = this.props
+    const { dispatch } = this.props
     ZoomManager.setZoom(zoomFactor)
     dispatch({
       type: 'SET_ZOOM',
@@ -46,7 +46,7 @@ class StatusBar extends React.Component {
   }
 
   render () {
-    let { config, status } = this.context
+    const { config, status } = this.context
 
     return (
       <div className='StatusBar'
diff --git a/browser/main/TopBar/index.js b/browser/main/TopBar/index.js
index 2c34ebf2..4ac48a80 100644
--- a/browser/main/TopBar/index.js
+++ b/browser/main/TopBar/index.js
@@ -2,15 +2,9 @@ import React, { PropTypes } from 'react'
 import CSSModules from 'browser/lib/CSSModules'
 import styles from './TopBar.styl'
 import _ from 'lodash'
-import NewNoteModal from 'browser/main/modals/NewNoteModal'
 import ee from 'browser/main/lib/eventEmitter'
 import NewNoteButton from 'browser/main/NewNoteButton'
 
-const { remote } = require('electron')
-const { dialog } = remote
-
-const OSX = window.process.platform === 'darwin'
-
 class TopBar extends React.Component {
   constructor (props) {
     super(props)
@@ -121,7 +115,7 @@ class TopBar extends React.Component {
   }
 
   render () {
-    let { config, style, data, location } = this.props
+    const { config, style, location } = this.props
     return (
       <div className='TopBar'
         styleName={config.isSideNavFolded ? 'root--expanded' : 'root'}
diff --git a/browser/main/index.js b/browser/main/index.js
index 35e81177..d7ed7bfd 100644
--- a/browser/main/index.js
+++ b/browser/main/index.js
@@ -36,7 +36,7 @@ document.addEventListener('click', function (e) {
   if (infoPanel) infoPanel.style.display = 'none'
 })
 
-let el = document.getElementById('content')
+const el = document.getElementById('content')
 const history = syncHistoryWithStore(hashHistory, store)
 
 function notify (...args) {
@@ -44,7 +44,7 @@ function notify (...args) {
 }
 
 function updateApp () {
-  let index = dialog.showMessageBox(remote.getCurrentWindow(), {
+  const index = dialog.showMessageBox(remote.getCurrentWindow(), {
     type: 'warning',
     message: 'Update Boostnote',
     detail: 'New Boostnote is ready to be installed.',
@@ -81,7 +81,7 @@ ReactDOM.render((
     </Router>
   </Provider>
 ), el, function () {
-  let loadingCover = document.getElementById('loadingCover')
+  const loadingCover = document.getElementById('loadingCover')
   loadingCover.parentNode.removeChild(loadingCover)
 
   ipcRenderer.on('update-ready', function () {
diff --git a/browser/main/lib/AwsMobileAnalyticsConfig.js b/browser/main/lib/AwsMobileAnalyticsConfig.js
index 4c0e15b5..f10d0b66 100644
--- a/browser/main/lib/AwsMobileAnalyticsConfig.js
+++ b/browser/main/lib/AwsMobileAnalyticsConfig.js
@@ -4,6 +4,7 @@ const ConfigManager = require('browser/main/lib/ConfigManager')
 
 const remote = require('electron').remote
 const os = require('os')
+let mobileAnalyticsClient
 
 AWS.config.region = 'us-east-1'
 if (process.env.NODE_ENV === 'production' && ConfigManager.default.get().amaEnabled) {
@@ -13,7 +14,7 @@ if (process.env.NODE_ENV === 'production' && ConfigManager.default.get().amaEnab
 
   const validPlatformName = convertPlatformName(os.platform())
 
-  const mobileAnalyticsClient = new AMA.Manager({
+  mobileAnalyticsClient = new AMA.Manager({
     appId: 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxx',
     appTitle: 'xxxxxxxxxx',
     appVersionName: remote.app.getVersion().toString(),
diff --git a/browser/main/lib/Commander.js b/browser/main/lib/Commander.js
index 959de5f0..6eef62ee 100644
--- a/browser/main/lib/Commander.js
+++ b/browser/main/lib/Commander.js
@@ -13,10 +13,10 @@ function release (el) {
 
 function fire (command) {
   console.info('COMMAND >>', command)
-  let splitted = command.split(':')
-  let target = splitted[0]
-  let targetCommand = splitted[1]
-  let targetCallees = callees
+  const splitted = command.split(':')
+  const target = splitted[0]
+  const targetCommand = splitted[1]
+  const targetCallees = callees
     .filter((callee) => callee.name === target)
 
   targetCallees.forEach((callee) => {
diff --git a/browser/main/lib/ConfigManager.js b/browser/main/lib/ConfigManager.js
index 7d50fda2..e200c855 100644
--- a/browser/main/lib/ConfigManager.js
+++ b/browser/main/lib/ConfigManager.js
@@ -6,8 +6,6 @@ const win = global.process.platform === 'win32'
 const electron = require('electron')
 const { ipcRenderer } = electron
 const consts = require('browser/lib/consts')
-const path = require('path')
-const fs = require('fs')
 
 let isInitialized = false
 
@@ -103,8 +101,8 @@ function get () {
 }
 
 function set (updates) {
-  let currentConfig = get()
-  let newConfig = Object.assign({}, DEFAULT_CONFIG, currentConfig, updates)
+  const currentConfig = get()
+  const newConfig = Object.assign({}, DEFAULT_CONFIG, currentConfig, updates)
   if (!validate(newConfig)) throw new Error('INVALID CONFIG')
   _save(newConfig)
 
@@ -123,7 +121,7 @@ function set (updates) {
     editorTheme.setAttribute('rel', 'stylesheet')
     document.head.appendChild(editorTheme)
   }
-  let newTheme = consts.THEMES.some((theme) => theme === newConfig.editor.theme)
+  const newTheme = consts.THEMES.some((theme) => theme === newConfig.editor.theme)
     ? newConfig.editor.theme
     : 'default'
 
@@ -141,7 +139,7 @@ function set (updates) {
 }
 
 function assignConfigValues (originalConfig, rcConfig) {
-  let config = Object.assign({}, DEFAULT_CONFIG, originalConfig, rcConfig)
+  const config = Object.assign({}, DEFAULT_CONFIG, originalConfig, rcConfig)
   config.hotkey = Object.assign({}, DEFAULT_CONFIG.hotkey, originalConfig.hotkey, rcConfig.hotkey)
   config.ui = Object.assign({}, DEFAULT_CONFIG.ui, originalConfig.ui, rcConfig.ui)
   config.editor = Object.assign({}, DEFAULT_CONFIG.editor, originalConfig.editor, rcConfig.editor)
diff --git a/browser/main/lib/ZoomManager.js b/browser/main/lib/ZoomManager.js
index 463df222..a8903ca3 100644
--- a/browser/main/lib/ZoomManager.js
+++ b/browser/main/lib/ZoomManager.js
@@ -19,7 +19,7 @@ function setZoom (zoomFactor, noSave = false) {
 }
 
 function getZoom () {
-  let config = ConfigManager.get()
+  const config = ConfigManager.get()
 
   return config.zoom
 }
diff --git a/browser/main/lib/dataApi/copyImage.js b/browser/main/lib/dataApi/copyImage.js
index 8f7fa656..ae79f8fb 100644
--- a/browser/main/lib/dataApi/copyImage.js
+++ b/browser/main/lib/dataApi/copyImage.js
@@ -1,7 +1,5 @@
 const fs = require('fs')
 const path = require('path')
-const _ = require('lodash')
-const sander = require('sander')
 const { findStorage } = require('browser/lib/findStorage')
 
 /**
diff --git a/browser/main/lib/dataApi/createFolder.js b/browser/main/lib/dataApi/createFolder.js
index 9357e17c..05fcea37 100644
--- a/browser/main/lib/dataApi/createFolder.js
+++ b/browser/main/lib/dataApi/createFolder.js
@@ -23,7 +23,6 @@ const { findStorage } = require('browser/lib/findStorage')
  * ```
  */
 function createFolder (storageKey, input) {
-  let rawStorages
   let targetStorage
   try {
     if (input == null) throw new Error('No input found.')
@@ -41,7 +40,7 @@ function createFolder (storageKey, input) {
       while (storage.folders.some((folder) => folder.key === key)) {
         key = keygen()
       }
-      let newFolder = {
+      const newFolder = {
         key,
         color: input.color,
         name: input.name
diff --git a/browser/main/lib/dataApi/createNote.js b/browser/main/lib/dataApi/createNote.js
index 29544ea6..91abdb08 100644
--- a/browser/main/lib/dataApi/createNote.js
+++ b/browser/main/lib/dataApi/createNote.js
@@ -66,7 +66,7 @@ function createNote (storageKey, input) {
           }
         }
       }
-      let noteData = Object.assign({}, input, {
+      const noteData = Object.assign({}, input, {
         key,
         createdAt: new Date(),
         updatedAt: new Date(),
diff --git a/browser/main/lib/dataApi/deleteFolder.js b/browser/main/lib/dataApi/deleteFolder.js
index c687382d..908677e1 100644
--- a/browser/main/lib/dataApi/deleteFolder.js
+++ b/browser/main/lib/dataApi/deleteFolder.js
@@ -19,7 +19,6 @@ const { findStorage } = require('browser/lib/findStorage')
  * ```
  */
 function deleteFolder (storageKey, folderKey) {
-  let rawStorages
   let targetStorage
   try {
     targetStorage = findStorage(storageKey)
@@ -38,17 +37,17 @@ function deleteFolder (storageKey, folderKey) {
         })
     })
     .then(function deleteFolderAndNotes (data) {
-      let { storage, notes } = data
+      const { storage, notes } = data
       storage.folders = storage.folders
         .filter(function excludeTargetFolder (folder) {
           return folder.key !== folderKey
         })
 
-      let targetNotes = notes.filter(function filterTargetNotes (note) {
+      const targetNotes = notes.filter(function filterTargetNotes (note) {
         return note.folder === folderKey
       })
 
-      let deleteAllNotes = targetNotes
+      const deleteAllNotes = targetNotes
         .map(function deleteNote (note) {
           const notePath = path.join(storage.path, 'notes', note.key + '.cson')
           return sander.unlink(notePath)
diff --git a/browser/main/lib/dataApi/deleteNote.js b/browser/main/lib/dataApi/deleteNote.js
index 52af55ab..49498a30 100644
--- a/browser/main/lib/dataApi/deleteNote.js
+++ b/browser/main/lib/dataApi/deleteNote.js
@@ -1,5 +1,4 @@
 const resolveStorageData = require('./resolveStorageData')
-const _ = require('lodash')
 const path = require('path')
 const sander = require('sander')
 const { findStorage } = require('browser/lib/findStorage')
@@ -14,7 +13,7 @@ function deleteNote (storageKey, noteKey) {
 
   return resolveStorageData(targetStorage)
     .then(function deleteNoteFile (storage) {
-      let notePath = path.join(storage.path, 'notes', noteKey + '.cson')
+      const notePath = path.join(storage.path, 'notes', noteKey + '.cson')
 
       try {
         sander.unlinkSync(notePath)
diff --git a/browser/main/lib/dataApi/init.js b/browser/main/lib/dataApi/init.js
index 67d853e0..7f81e90b 100644
--- a/browser/main/lib/dataApi/init.js
+++ b/browser/main/lib/dataApi/init.js
@@ -20,7 +20,7 @@ const CSON = require('@rokt33r/season')
  * 3. empty directory
  */
 function init () {
-  let fetchStorages = function () {
+  const fetchStorages = function () {
     let rawStorages
     try {
       rawStorages = JSON.parse(window.localStorage.getItem('storages'))
@@ -34,8 +34,8 @@ function init () {
       .map(resolveStorageData))
   }
 
-  let fetchNotes = function (storages) {
-    let findNotesFromEachStorage = storages
+  const fetchNotes = function (storages) {
+    const findNotesFromEachStorage = storages
       .map((storage) => {
         return resolveStorageNotes(storage)
           .then((notes) => {
diff --git a/browser/main/lib/dataApi/migrateFromV5Storage.js b/browser/main/lib/dataApi/migrateFromV5Storage.js
index be922731..b11e66e9 100644
--- a/browser/main/lib/dataApi/migrateFromV5Storage.js
+++ b/browser/main/lib/dataApi/migrateFromV5Storage.js
@@ -9,7 +9,7 @@ const sander = require('sander')
 function migrateFromV5Storage (storageKey, data) {
   let targetStorage
   try {
-    let cachedStorageList = JSON.parse(localStorage.getItem('storages'))
+    const cachedStorageList = JSON.parse(localStorage.getItem('storages'))
     if (!_.isArray(cachedStorageList)) throw new Error('Target storage doesn\'t exist.')
 
     targetStorage = _.find(cachedStorageList, {key: storageKey})
@@ -24,15 +24,15 @@ function migrateFromV5Storage (storageKey, data) {
 }
 
 function importAll (storage, data) {
-  let oldArticles = data.articles
-  let notes = []
+  const oldArticles = data.articles
+  const notes = []
   data.folders
     .forEach(function (oldFolder) {
       let folderKey = keygen()
       while (storage.folders.some((folder) => folder.key === folderKey)) {
         folderKey = keygen()
       }
-      let newFolder = {
+      const newFolder = {
         key: folderKey,
         name: oldFolder.name,
         color: consts.FOLDER_COLORS[Math.floor(Math.random() * 7) % 7]
@@ -40,7 +40,7 @@ function importAll (storage, data) {
 
       storage.folders.push(newFolder)
 
-      let articles = oldArticles.filter((article) => article.FolderKey === oldFolder.key)
+      const articles = oldArticles.filter((article) => article.FolderKey === oldFolder.key)
       articles.forEach((article) => {
         let noteKey = keygen()
         let isUnique = false
@@ -59,7 +59,7 @@ function importAll (storage, data) {
         }
 
         if (article.mode === 'markdown') {
-          let newNote = {
+          const newNote = {
             tags: article.tags,
             createdAt: article.createdAt,
             updatedAt: article.updatedAt,
@@ -73,7 +73,7 @@ function importAll (storage, data) {
           }
           notes.push(newNote)
         } else {
-          let newNote = {
+          const newNote = {
             tags: article.tags,
             createdAt: article.createdAt,
             updatedAt: article.updatedAt,
diff --git a/browser/main/lib/dataApi/moveNote.js b/browser/main/lib/dataApi/moveNote.js
index da44211d..4580062e 100644
--- a/browser/main/lib/dataApi/moveNote.js
+++ b/browser/main/lib/dataApi/moveNote.js
@@ -20,7 +20,7 @@ function moveNote (storageKey, noteKey, newStorageKey, newFolderKey) {
     .then(function saveNote (_oldStorage) {
       oldStorage = _oldStorage
       let noteData
-      let notePath = path.join(oldStorage.path, 'notes', noteKey + '.cson')
+      const notePath = path.join(oldStorage.path, 'notes', noteKey + '.cson')
       try {
         noteData = CSON.readFileSync(notePath)
       } catch (err) {
diff --git a/browser/main/lib/dataApi/renameStorage.js b/browser/main/lib/dataApi/renameStorage.js
index 3c82130d..78242bed 100644
--- a/browser/main/lib/dataApi/renameStorage.js
+++ b/browser/main/lib/dataApi/renameStorage.js
@@ -1,6 +1,5 @@
 const _ = require('lodash')
 const resolveStorageData = require('./resolveStorageData')
-const { findStorage } = require('browser/lib/findStorage')
 
 /**
  * @param {String} key
@@ -19,7 +18,7 @@ function renameStorage (key, name) {
     console.error(err)
     return Promise.reject(err)
   }
-  let targetStorage = _.find(cachedStorageList, {key: key})
+  const targetStorage = _.find(cachedStorageList, {key: key})
   if (targetStorage == null) return Promise.reject('Storage')
 
   targetStorage.name = name
diff --git a/browser/main/lib/dataApi/reorderFolder.js b/browser/main/lib/dataApi/reorderFolder.js
index 3ee9229e..9102438e 100644
--- a/browser/main/lib/dataApi/reorderFolder.js
+++ b/browser/main/lib/dataApi/reorderFolder.js
@@ -18,7 +18,6 @@ const { findStorage } = require('browser/lib/findStorage')
  * ```
  */
 function reorderFolder (storageKey, oldIndex, newIndex) {
-  let rawStorages
   let targetStorage
   try {
     if (!_.isNumber(oldIndex)) throw new Error('oldIndex must be a number.')
diff --git a/browser/main/lib/dataApi/resolveStorageData.js b/browser/main/lib/dataApi/resolveStorageData.js
index e25ab16d..af040c5d 100644
--- a/browser/main/lib/dataApi/resolveStorageData.js
+++ b/browser/main/lib/dataApi/resolveStorageData.js
@@ -4,7 +4,7 @@ const CSON = require('@rokt33r/season')
 const migrateFromV6Storage = require('./migrateFromV6Storage')
 
 function resolveStorageData (storageCache) {
-  let storage = {
+  const storage = {
     key: storageCache.key,
     name: storageCache.name,
     type: storageCache.type,
@@ -13,7 +13,7 @@ function resolveStorageData (storageCache) {
 
   const boostnoteJSONPath = path.join(storageCache.path, 'boostnote.json')
   try {
-    let jsonData = CSON.readFileSync(boostnoteJSONPath)
+    const jsonData = CSON.readFileSync(boostnoteJSONPath)
     if (!_.isArray(jsonData.folders)) throw new Error('folders should be an array.')
     storage.folders = jsonData.folders
     storage.version = jsonData.version
@@ -28,7 +28,7 @@ function resolveStorageData (storageCache) {
     storage.version = '1.0'
   }
 
-  let version = parseInt(storage.version, 10)
+  const version = parseInt(storage.version, 10)
   if (version >= 1) {
     if (version > 1) {
       console.log('The repository version is newer than one of current app.')
diff --git a/browser/main/lib/dataApi/resolveStorageNotes.js b/browser/main/lib/dataApi/resolveStorageNotes.js
index 104b0c00..5684f06e 100644
--- a/browser/main/lib/dataApi/resolveStorageNotes.js
+++ b/browser/main/lib/dataApi/resolveStorageNotes.js
@@ -16,13 +16,13 @@ function resolveStorageNotes (storage) {
     }
     notePathList = []
   }
-  let notes = notePathList
+  const notes = notePathList
     .filter(function filterOnlyCSONFile (notePath) {
       return /\.cson$/.test(notePath)
     })
     .map(function parseCSONFile (notePath) {
       try {
-        let data = CSON.readFileSync(path.join(notesDirPath, notePath))
+        const data = CSON.readFileSync(path.join(notesDirPath, notePath))
         data.key = path.basename(notePath, '.cson')
         data.storage = storage.key
         return data
diff --git a/browser/main/lib/dataApi/updateFolder.js b/browser/main/lib/dataApi/updateFolder.js
index 6c6e587b..2a325c60 100644
--- a/browser/main/lib/dataApi/updateFolder.js
+++ b/browser/main/lib/dataApi/updateFolder.js
@@ -23,7 +23,6 @@ const { findStorage } = require('browser/lib/findStorage')
  * ```
  */
 function updateFolder (storageKey, folderKey, input) {
-  let rawStorages
   let targetStorage
   try {
     if (input == null) throw new Error('No input found.')
@@ -37,7 +36,7 @@ function updateFolder (storageKey, folderKey, input) {
 
   return resolveStorageData(targetStorage)
     .then(function updateFolder (storage) {
-      let targetFolder = _.find(storage.folders, {key: folderKey})
+      const targetFolder = _.find(storage.folders, {key: folderKey})
       if (targetFolder == null) throw new Error('Target folder doesn\'t exist.')
       targetFolder.name = input.name
       targetFolder.color = input.color
diff --git a/browser/main/lib/dataApi/updateNote.js b/browser/main/lib/dataApi/updateNote.js
index cf3fc047..2fbd52c2 100644
--- a/browser/main/lib/dataApi/updateNote.js
+++ b/browser/main/lib/dataApi/updateNote.js
@@ -5,7 +5,7 @@ const CSON = require('@rokt33r/season')
 const { findStorage } = require('browser/lib/findStorage')
 
 function validateInput (input) {
-  let validatedInput = {}
+  const validatedInput = {}
 
   if (input.tags != null) {
     if (!_.isArray(input.tags)) validatedInput.tags = []
@@ -81,7 +81,7 @@ function updateNote (storageKey, noteKey, input) {
   return resolveStorageData(targetStorage)
     .then(function saveNote (storage) {
       let noteData
-      let notePath = path.join(storage.path, 'notes', noteKey + '.cson')
+      const notePath = path.join(storage.path, 'notes', noteKey + '.cson')
       try {
         noteData = CSON.readFileSync(notePath)
       } catch (err) {
diff --git a/browser/main/lib/modal.js b/browser/main/lib/modal.js
index 1964d52e..7a7a9c8c 100644
--- a/browser/main/lib/modal.js
+++ b/browser/main/lib/modal.js
@@ -16,7 +16,7 @@ class ModalBase extends React.Component {
   close () {
     if (modalBase != null) modalBase.setState({component: null, componentProps: null, isHidden: true})
     // Toggle overflow style on NoteList
-    let list = document.querySelector('.NoteList__list___browser-main-NoteList-')
+    const list = document.querySelector('.NoteList__list___browser-main-NoteList-')
     list.style.overflow = 'auto'
   }
 
@@ -34,14 +34,14 @@ class ModalBase extends React.Component {
   }
 }
 
-let el = document.createElement('div')
+const el = document.createElement('div')
 document.body.appendChild(el)
-let modalBase = ReactDOM.render(<ModalBase />, el)
+const modalBase = ReactDOM.render(<ModalBase />, el)
 
 export function openModal (component, props) {
   if (modalBase == null) { return }
   // Hide scrollbar by removing overflow when modal opens
-  let list = document.querySelector('.NoteList__list___browser-main-NoteList-')
+  const list = document.querySelector('.NoteList__list___browser-main-NoteList-')
   list.style.overflow = 'hidden'
   document.body.setAttribute('data-modal', 'open')
   modalBase.setState({component: component, componentProps: props, isHidden: false})
diff --git a/browser/main/modals/CreateFolderModal.js b/browser/main/modals/CreateFolderModal.js
index 1ac0ee97..5ef18ac9 100644
--- a/browser/main/modals/CreateFolderModal.js
+++ b/browser/main/modals/CreateFolderModal.js
@@ -51,8 +51,8 @@ class CreateFolderModal extends React.Component {
   confirm () {
     AwsMobileAnalyticsConfig.recordDynamicCustomEvent('ADD_FOLDER')
     if (this.state.name.trim().length > 0) {
-      let { storage } = this.props
-      let input = {
+      const { storage } = this.props
+      const input = {
         name: this.state.name.trim(),
         color: consts.FOLDER_COLORS[Math.floor(Math.random() * 7) % 7]
       }
diff --git a/browser/main/modals/InitModal.js b/browser/main/modals/InitModal.js
index 4e432bcb..b8a94cf4 100644
--- a/browser/main/modals/InitModal.js
+++ b/browser/main/modals/InitModal.js
@@ -13,9 +13,9 @@ const electron = require('electron')
 const { remote } = electron
 
 function browseFolder () {
-  let dialog = remote.dialog
+  const dialog = remote.dialog
 
-  let defaultPath = remote.app.getPath('home')
+  const defaultPath = remote.app.getPath('home')
   return new Promise((resolve, reject) => {
     dialog.showOpenDialog({
       title: 'Select Directory',
@@ -55,7 +55,7 @@ class InitModal extends React.Component {
     } catch (err) {
       console.error(err)
     }
-    let newState = {
+    const newState = {
       isLoading: false
     }
     if (data != null) {
@@ -122,7 +122,7 @@ class InitModal extends React.Component {
             notes: data.notes
           })
 
-          let defaultSnippetNote = dataApi
+          const defaultSnippetNote = dataApi
             .createNote(data.storage.key, {
               type: 'SNIPPET_NOTE',
               folder: data.storage.folders[0].key,
@@ -147,7 +147,7 @@ class InitModal extends React.Component {
                 note: note
               })
             })
-          let defaultMarkdownNote = dataApi
+          const defaultMarkdownNote = dataApi
             .createNote(data.storage.key, {
               type: 'MARKDOWN_NOTE',
               folder: data.storage.folders[0].key,
diff --git a/browser/main/modals/NewNoteModal.js b/browser/main/modals/NewNoteModal.js
index 4e794832..346fe920 100644
--- a/browser/main/modals/NewNoteModal.js
+++ b/browser/main/modals/NewNoteModal.js
@@ -26,7 +26,7 @@ class NewNoteModal extends React.Component {
   handleMarkdownNoteButtonClick (e) {
     AwsMobileAnalyticsConfig.recordDynamicCustomEvent('ADD_MARKDOWN')
     AwsMobileAnalyticsConfig.recordDynamicCustomEvent('ADD_ALLNOTE')
-    let { storage, folder, dispatch, location } = this.props
+    const { storage, folder, dispatch, location } = this.props
     dataApi
       .createNote(storage, {
         type: 'MARKDOWN_NOTE',
@@ -58,7 +58,7 @@ class NewNoteModal extends React.Component {
   handleSnippetNoteButtonClick (e) {
     AwsMobileAnalyticsConfig.recordDynamicCustomEvent('ADD_SNIPPET')
     AwsMobileAnalyticsConfig.recordDynamicCustomEvent('ADD_ALLNOTE')
-    let { storage, folder, dispatch, location } = this.props
+    const { storage, folder, dispatch, location } = this.props
 
     dataApi
       .createNote(storage, {
diff --git a/browser/main/modals/PreferencesModal/FolderItem.js b/browser/main/modals/PreferencesModal/FolderItem.js
index 5bd9d9f1..f30f113a 100644
--- a/browser/main/modals/PreferencesModal/FolderItem.js
+++ b/browser/main/modals/PreferencesModal/FolderItem.js
@@ -23,7 +23,7 @@ class FolderItem extends React.Component {
   }
 
   handleEditChange (e) {
-    let { folder } = this.state
+    const { folder } = this.state
 
     folder.name = this.refs.nameInput.value
     this.setState({
@@ -36,7 +36,7 @@ class FolderItem extends React.Component {
   }
 
   confirm () {
-    let { storage, folder } = this.props
+    const { storage, folder } = this.props
     dataApi
       .updateFolder(storage.key, folder.key, {
         color: this.state.folder.color,
@@ -162,7 +162,7 @@ class FolderItem extends React.Component {
   }
 
   handleDeleteConfirmButtonClick (e) {
-    let { storage, folder } = this.props
+    const { storage, folder } = this.props
     dataApi
       .deleteFolder(storage.key, folder.key)
       .then((data) => {
@@ -197,8 +197,8 @@ class FolderItem extends React.Component {
   }
 
   handleEditButtonClick (e) {
-    let { folder: propsFolder } = this.props
-    let { folder: stateFolder } = this.state
+    const { folder: propsFolder } = this.props
+    const { folder: stateFolder } = this.state
     const folder = Object.assign({}, stateFolder, propsFolder)
     this.setState({
       status: 'EDIT',
@@ -215,7 +215,7 @@ class FolderItem extends React.Component {
   }
 
   renderIdle () {
-    let { folder } = this.props
+    const { folder } = this.props
     return (
       <div styleName='folderItem'
         onDoubleClick={(e) => this.handleEditButtonClick(e)}
diff --git a/browser/main/modals/PreferencesModal/FolderList.js b/browser/main/modals/PreferencesModal/FolderList.js
index 0172dc10..a3313d35 100644
--- a/browser/main/modals/PreferencesModal/FolderList.js
+++ b/browser/main/modals/PreferencesModal/FolderList.js
@@ -4,13 +4,13 @@ import dataApi from 'browser/main/lib/dataApi'
 import styles from './FolderList.styl'
 import store from 'browser/main/store'
 import FolderItem from './FolderItem'
-import { SortableContainer, arrayMove } from 'react-sortable-hoc'
+import { SortableContainer } from 'react-sortable-hoc'
 
 class FolderList extends React.Component {
   render () {
-    let { storage, hostBoundingBox } = this.props
+    const { storage, hostBoundingBox } = this.props
 
-    let folderList = storage.folders.map((folder, index) => {
+    const folderList = storage.folders.map((folder, index) => {
       return <FolderItem key={folder.key}
         folder={folder}
         storage={storage}
@@ -53,7 +53,7 @@ class SortableFolderListComponent extends React.Component {
   constructor (props) {
     super(props)
     this.onSortEnd = ({oldIndex, newIndex}) => {
-      let { storage } = this.props
+      const { storage } = this.props
       dataApi
         .reorderFolder(storage.key, oldIndex, newIndex)
         .then((data) => {
diff --git a/browser/main/modals/PreferencesModal/HotkeyTab.js b/browser/main/modals/PreferencesModal/HotkeyTab.js
index 18ac31ff..49f476de 100644
--- a/browser/main/modals/PreferencesModal/HotkeyTab.js
+++ b/browser/main/modals/PreferencesModal/HotkeyTab.js
@@ -41,7 +41,7 @@ class HotkeyTab extends React.Component {
   }
 
   handleSaveButtonClick (e) {
-    let newConfig = {
+    const newConfig = {
       hotkey: this.state.config.hotkey
     }
 
@@ -61,7 +61,7 @@ class HotkeyTab extends React.Component {
   }
 
   handleHotkeyChange (e) {
-    let { config } = this.state
+    const { config } = this.state
     config.hotkey = {
       toggleFinder: this.refs.toggleFinder.value,
       toggleMain: this.refs.toggleMain.value
@@ -80,13 +80,13 @@ class HotkeyTab extends React.Component {
   }
 
   render () {
-    let keymapAlert = this.state.keymapAlert
-    let keymapAlertElement = keymapAlert != null
+    const keymapAlert = this.state.keymapAlert
+    const keymapAlertElement = keymapAlert != null
       ? <p className={`alert ${keymapAlert.type}`}>
         {keymapAlert.message}
       </p>
       : null
-    let { config } = this.state
+    const { config } = this.state
 
     return (
       <div styleName='root'>
diff --git a/browser/main/modals/PreferencesModal/StorageItem.js b/browser/main/modals/PreferencesModal/StorageItem.js
index 478e4c44..0e8388c2 100644
--- a/browser/main/modals/PreferencesModal/StorageItem.js
+++ b/browser/main/modals/PreferencesModal/StorageItem.js
@@ -19,8 +19,8 @@ class StorageItem extends React.Component {
   }
 
   handleNewFolderButtonClick (e) {
-    let { storage } = this.props
-    let input = {
+    const { storage } = this.props
+    const input = {
       name: 'Untitled',
       color: consts.FOLDER_COLORS[Math.floor(Math.random() * 7) % 7]
     }
@@ -38,12 +38,12 @@ class StorageItem extends React.Component {
   }
 
   handleExternalButtonClick () {
-    let { storage } = this.props
+    const { storage } = this.props
     shell.showItemInFolder(storage.path)
   }
 
   handleUnlinkButtonClick (e) {
-    let index = dialog.showMessageBox(remote.getCurrentWindow(), {
+    const index = dialog.showMessageBox(remote.getCurrentWindow(), {
       type: 'warning',
       message: 'Unlink Storage',
       detail: 'Unlinking removes this linked storage from Boostnote. No data is removed, please manually delete the folder from your hard drive if needed.',
@@ -51,7 +51,7 @@ class StorageItem extends React.Component {
     })
 
     if (index === 0) {
-      let { storage } = this.props
+      const { storage } = this.props
       dataApi.removeStorage(storage.key)
         .then(() => {
           store.dispatch({
@@ -66,7 +66,7 @@ class StorageItem extends React.Component {
   }
 
   handleLabelClick (e) {
-    let { storage } = this.props
+    const { storage } = this.props
     this.setState({
       isLabelEditing: true,
       name: storage.name
@@ -81,7 +81,7 @@ class StorageItem extends React.Component {
   }
 
   handleLabelBlur (e) {
-    let { storage } = this.props
+    const { storage } = this.props
     dataApi
       .renameStorage(storage.key, this.state.name)
       .then((_storage) => {
@@ -96,7 +96,7 @@ class StorageItem extends React.Component {
   }
 
   render () {
-    let { storage, hostBoundingBox } = this.props
+    const { storage, hostBoundingBox } = this.props
 
     return (
       <div styleName='root' key={storage.key}>
diff --git a/browser/main/modals/PreferencesModal/StoragesTab.js b/browser/main/modals/PreferencesModal/StoragesTab.js
index 641e5e8c..41a7cc24 100644
--- a/browser/main/modals/PreferencesModal/StoragesTab.js
+++ b/browser/main/modals/PreferencesModal/StoragesTab.js
@@ -8,9 +8,9 @@ const electron = require('electron')
 const { shell, remote } = electron
 
 function browseFolder () {
-  let dialog = remote.dialog
+  const dialog = remote.dialog
 
-  let defaultPath = remote.app.getPath('home')
+  const defaultPath = remote.app.getPath('home')
   return new Promise((resolve, reject) => {
     dialog.showOpenDialog({
       title: 'Select Directory',
@@ -56,10 +56,10 @@ class StoragesTab extends React.Component {
   }
 
   renderList () {
-    let { data, boundingBox } = this.props
+    const { data, boundingBox } = this.props
 
     if (!boundingBox) { return null }
-    let storageList = data.storageMap.map((storage) => {
+    const storageList = data.storageMap.map((storage) => {
       return <StorageItem
         key={storage.key}
         storage={storage}
@@ -88,7 +88,7 @@ class StoragesTab extends React.Component {
     browseFolder()
       .then((targetPath) => {
         if (targetPath.length > 0) {
-          let { newStorage } = this.state
+          const { newStorage } = this.state
           newStorage.path = targetPath
           this.setState({
             newStorage
@@ -102,7 +102,7 @@ class StoragesTab extends React.Component {
   }
 
   handleAddStorageChange (e) {
-    let { newStorage } = this.state
+    const { newStorage } = this.state
     newStorage.name = this.refs.addStorageName.value
     newStorage.path = this.refs.addStoragePath.value
     this.setState({
@@ -117,7 +117,7 @@ class StoragesTab extends React.Component {
         path: this.state.newStorage.path
       })
       .then((data) => {
-        let { dispatch } = this.props
+        const { dispatch } = this.props
         dispatch({
           type: 'ADD_STORAGE',
           storage: data.storage,
diff --git a/browser/main/modals/PreferencesModal/UiTab.js b/browser/main/modals/PreferencesModal/UiTab.js
index 8c1e8a4c..8c670623 100644
--- a/browser/main/modals/PreferencesModal/UiTab.js
+++ b/browser/main/modals/PreferencesModal/UiTab.js
@@ -119,8 +119,8 @@ class UiTab extends React.Component {
   }
 
   render () {
-    let UiAlert = this.state.UiAlert
-    let UiAlertElement = UiAlert != null
+    const UiAlert = this.state.UiAlert
+    const UiAlertElement = UiAlert != null
       ? <p className={`alert ${UiAlert.type}`}>
         {UiAlert.message}
       </p>
diff --git a/browser/main/modals/PreferencesModal/index.js b/browser/main/modals/PreferencesModal/index.js
index 059e4481..0550c2b3 100644
--- a/browser/main/modals/PreferencesModal/index.js
+++ b/browser/main/modals/PreferencesModal/index.js
@@ -42,7 +42,7 @@ class Preferences extends React.Component {
 
   renderContent () {
     const { boundingBox } = this.state
-    let { dispatch, config, data } = this.props
+    const { dispatch, config, data } = this.props
 
     switch (this.state.currentTab) {
       case 'INFO':
@@ -94,9 +94,9 @@ class Preferences extends React.Component {
   }
 
   render () {
-    let content = this.renderContent()
+    const content = this.renderContent()
 
-    let tabs = [
+    const tabs = [
       {target: 'STORAGES', label: 'Storages'},
       {target: 'HOTKEY', label: 'Hotkey'},
       {target: 'UI', label: 'UI'},
@@ -104,8 +104,8 @@ class Preferences extends React.Component {
       {target: 'CROWDFUNDING', label: 'Crowdfunding'}
     ]
 
-    let navButtons = tabs.map((tab) => {
-      let isActive = this.state.currentTab === tab.target
+    const navButtons = tabs.map((tab) => {
+      const isActive = this.state.currentTab === tab.target
       return (
         <button styleName={isActive
             ? 'nav-button--active'
diff --git a/browser/main/modals/RenameFolderModal.js b/browser/main/modals/RenameFolderModal.js
index 09e86632..0386b538 100644
--- a/browser/main/modals/RenameFolderModal.js
+++ b/browser/main/modals/RenameFolderModal.js
@@ -48,7 +48,7 @@ class RenameFolderModal extends React.Component {
 
   confirm () {
     if (this.state.name.trim().length > 0) {
-      let { storage, folder } = this.props
+      const { storage, folder } = this.props
       dataApi
         .updateFolder(storage.key, folder.key, {
           name: this.state.name,
diff --git a/browser/main/store.js b/browser/main/store.js
index ac41b1d0..647d0ac9 100644
--- a/browser/main/store.js
+++ b/browser/main/store.js
@@ -27,8 +27,8 @@ function data (state = defaultDataMap(), action) {
 
       action.notes.some((note) => {
         if (note === undefined) return true
-        let uniqueKey = note.storage + '-' + note.key
-        let folderKey = note.storage + '-' + note.folder
+        const uniqueKey = note.storage + '-' + note.key
+        const folderKey = note.storage + '-' + note.folder
         state.noteMap.set(uniqueKey, note)
 
         if (note.isStarred) {
@@ -65,10 +65,10 @@ function data (state = defaultDataMap(), action) {
       return state
     case 'UPDATE_NOTE':
       {
-        let note = action.note
-        let uniqueKey = note.storage + '-' + note.key
-        let folderKey = note.storage + '-' + note.folder
-        let oldNote = state.noteMap.get(uniqueKey)
+        const note = action.note
+        const uniqueKey = note.storage + '-' + note.key
+        const folderKey = note.storage + '-' + note.folder
+        const oldNote = state.noteMap.get(uniqueKey)
 
         state = Object.assign({}, state)
         state.noteMap = new Map(state.noteMap)
@@ -110,7 +110,7 @@ function data (state = defaultDataMap(), action) {
           state.folderNoteMap.set(folderKey, folderNoteSet)
 
           if (oldNote != null) {
-            let oldFolderKey = oldNote.storage + '-' + oldNote.folder
+            const oldFolderKey = oldNote.storage + '-' + oldNote.folder
             let oldFolderNoteList = state.folderNoteMap.get(oldFolderKey)
             oldFolderNoteList = new Set(oldFolderNoteList)
             oldFolderNoteList.delete(uniqueKey)
@@ -119,8 +119,8 @@ function data (state = defaultDataMap(), action) {
         }
 
         if (oldNote != null) {
-          let discardedTags = _.difference(oldNote.tags, note.tags)
-          let addedTags = _.difference(note.tags, oldNote.tags)
+          const discardedTags = _.difference(oldNote.tags, note.tags)
+          const addedTags = _.difference(note.tags, oldNote.tags)
           if (discardedTags.length + addedTags.length > 0) {
             state.tagNoteMap = new Map(state.tagNoteMap)
 
@@ -156,12 +156,12 @@ function data (state = defaultDataMap(), action) {
       }
     case 'MOVE_NOTE':
       {
-        let originNote = action.originNote
-        let originKey = originNote.storage + '-' + originNote.key
-        let note = action.note
-        let uniqueKey = note.storage + '-' + note.key
-        let folderKey = note.storage + '-' + note.folder
-        let oldNote = state.noteMap.get(uniqueKey)
+        const originNote = action.originNote
+        const originKey = originNote.storage + '-' + originNote.key
+        const note = action.note
+        const uniqueKey = note.storage + '-' + note.key
+        const folderKey = note.storage + '-' + note.folder
+        const oldNote = state.noteMap.get(uniqueKey)
 
         state = Object.assign({}, state)
         state.noteMap = new Map(state.noteMap)
@@ -191,7 +191,7 @@ function data (state = defaultDataMap(), action) {
 
           // From folderNoteMap
           state.folderNoteMap = new Map(state.folderNoteMap)
-          let originFolderKey = originNote.storage + '-' + originNote.folder
+          const originFolderKey = originNote.storage + '-' + originNote.folder
           let originFolderList = state.folderNoteMap.get(originFolderKey)
           originFolderList = new Set(originFolderList)
           originFolderList.delete(originKey)
@@ -245,7 +245,7 @@ function data (state = defaultDataMap(), action) {
           state.folderNoteMap.set(folderKey, folderNoteList)
 
           if (oldNote != null) {
-            let oldFolderKey = oldNote.storage + '-' + oldNote.folder
+            const oldFolderKey = oldNote.storage + '-' + oldNote.folder
             let oldFolderNoteList = state.folderNoteMap.get(oldFolderKey)
             oldFolderNoteList = new Set(oldFolderNoteList)
             oldFolderNoteList.delete(uniqueKey)
@@ -255,8 +255,8 @@ function data (state = defaultDataMap(), action) {
 
         // Remove from old folder map
         if (oldNote != null) {
-          let discardedTags = _.difference(oldNote.tags, note.tags)
-          let addedTags = _.difference(note.tags, oldNote.tags)
+          const discardedTags = _.difference(oldNote.tags, note.tags)
+          const addedTags = _.difference(note.tags, oldNote.tags)
           if (discardedTags.length + addedTags.length > 0) {
             state.tagNoteMap = new Map(state.tagNoteMap)
 
@@ -292,8 +292,8 @@ function data (state = defaultDataMap(), action) {
       }
     case 'DELETE_NOTE':
       {
-        let uniqueKey = action.storageKey + '-' + action.noteKey
-        let targetNote = state.noteMap.get(uniqueKey)
+        const uniqueKey = action.storageKey + '-' + action.noteKey
+        const targetNote = state.noteMap.get(uniqueKey)
 
         state = Object.assign({}, state)
 
@@ -317,7 +317,7 @@ function data (state = defaultDataMap(), action) {
           }
 
           // From folderNoteMap
-          let folderKey = targetNote.storage + '-' + targetNote.folder
+          const folderKey = targetNote.storage + '-' + targetNote.folder
           state.folderNoteMap = new Map(state.folderNoteMap)
           let folderSet = state.folderNoteMap.get(folderKey)
           folderSet = new Set(folderSet)
@@ -340,18 +340,14 @@ function data (state = defaultDataMap(), action) {
         return state
       }
     case 'UPDATE_FOLDER':
-      {
-        state = Object.assign({}, state)
-        state.storageMap = new Map(state.storageMap)
-        state.storageMap.set(action.storage.key, action.storage)
-      }
+      state = Object.assign({}, state)
+      state.storageMap = new Map(state.storageMap)
+      state.storageMap.set(action.storage.key, action.storage)
       return state
     case 'REORDER_FOLDER':
-      {
-        state = Object.assign({}, state)
-        state.storageMap = new Map(state.storageMap)
-        state.storageMap.set(action.storage.key, action.storage)
-      }
+      state = Object.assign({}, state)
+      state.storageMap = new Map(state.storageMap)
+      state.storageMap.set(action.storage.key, action.storage)
       return state
     case 'DELETE_FOLDER':
       {
@@ -361,8 +357,8 @@ function data (state = defaultDataMap(), action) {
 
         // Get note list from folder-note map
         // and delete note set from folder-note map
-        let folderKey = action.storage.key + '-' + action.folderKey
-        let noteSet = state.folderNoteMap.get(folderKey)
+        const folderKey = action.storage.key + '-' + action.folderKey
+        const noteSet = state.folderNoteMap.get(folderKey)
         state.folderNoteMap = new Map(state.folderNoteMap)
         state.folderNoteMap.delete(folderKey)
 
@@ -375,7 +371,7 @@ function data (state = defaultDataMap(), action) {
         if (noteSet != null) {
           noteSet.forEach(function handleNoteKey (noteKey) {
             // Get note from noteMap
-            let note = state.noteMap.get(noteKey)
+            const note = state.noteMap.get(noteKey)
             if (note != null) {
               state.noteMap.delete(noteKey)
 
@@ -417,8 +413,8 @@ function data (state = defaultDataMap(), action) {
       state.folderNoteMap = new Map(state.folderNoteMap)
       state.tagNoteMap = new Map(state.tagNoteMap)
       action.notes.forEach((note) => {
-        let uniqueKey = note.storage + '-' + note.key
-        let folderKey = note.storage + '-' + note.folder
+        const uniqueKey = note.storage + '-' + note.key
+        const folderKey = note.storage + '-' + note.folder
         state.noteMap.set(uniqueKey, note)
 
         if (note.isStarred) {
@@ -451,7 +447,7 @@ function data (state = defaultDataMap(), action) {
       return state
     case 'REMOVE_STORAGE':
       state = Object.assign({}, state)
-      let storage = state.storageMap.get(action.storageKey)
+      const storage = state.storageMap.get(action.storageKey)
       state.storageMap = new Map(state.storageMap)
       state.storageMap.delete(action.storageKey)
 
@@ -459,17 +455,17 @@ function data (state = defaultDataMap(), action) {
       if (storage != null) {
         state.folderMap = new Map(state.folderMap)
         storage.folders.forEach((folder) => {
-          let folderKey = storage.key + '-' + folder.key
+          const folderKey = storage.key + '-' + folder.key
           state.folderMap.delete(folderKey)
         })
       }
 
       // Remove notes from noteMap and tagNoteMap
-      let storageNoteSet = state.storageNoteMap.get(action.storageKey)
+      const storageNoteSet = state.storageNoteMap.get(action.storageKey)
       state.storageNoteMap = new Map(state.storageNoteMap)
       state.storageNoteMap.delete(action.storageKey)
       if (storageNoteSet != null) {
-        let notes = storageNoteSet
+        const notes = storageNoteSet
           .map((noteKey) => state.noteMap.get(noteKey))
           .filter((note) => note != null)
 
@@ -477,7 +473,7 @@ function data (state = defaultDataMap(), action) {
         state.tagNoteMap = new Map(state.tagNoteMap)
         state.starredSet = new Set(state.starredSet)
         notes.forEach((note) => {
-          let noteKey = storage.key + '-' + note.key
+          const noteKey = storage.key + '-' + note.key
           state.noteMap.delete(noteKey)
           state.starredSet.delete(noteKey)
           note.tags.forEach((tag) => {
@@ -535,13 +531,13 @@ function status (state = defaultStatus, action) {
   return state
 }
 
-let reducer = combineReducers({
+const reducer = combineReducers({
   data,
   config,
   status,
   routing: routerReducer
 })
 
-let store = createStore(reducer)
+const store = createStore(reducer)
 
 export default store
diff --git a/tests/dataApi/addStorage.js b/tests/dataApi/addStorage.js
index d5bc2994..da39a993 100644
--- a/tests/dataApi/addStorage.js
+++ b/tests/dataApi/addStorage.js
@@ -36,7 +36,7 @@ test.serial('Add Storage', (t) => {
       return addStorage(input)
     })
     .then(function validateResult (data) {
-      let { storage, notes } = data
+      const { storage, notes } = data
 
       // Check data.storage
       t.true(_.isString(storage.key))
@@ -53,13 +53,13 @@ test.serial('Add Storage', (t) => {
       })
 
       // Check localStorage
-      let cacheData = _.find(JSON.parse(localStorage.getItem('storages')), {key: data.storage.key})
+      const cacheData = _.find(JSON.parse(localStorage.getItem('storages')), {key: data.storage.key})
       t.is(cacheData.name, input.name)
       t.is(cacheData.type, input.type)
       t.is(cacheData.path, input.path)
 
       // Check boostnote.json
-      let jsonData = CSON.readFileSync(path.join(storage.path, 'boostnote.json'))
+      const jsonData = CSON.readFileSync(path.join(storage.path, 'boostnote.json'))
       t.true(_.isArray(jsonData.folders))
       t.is(jsonData.version, '1.0')
       t.is(jsonData.folders.length, t.context.v1StorageData.json.folders.length)
diff --git a/tests/dataApi/createFolder-test.js b/tests/dataApi/createFolder-test.js
index 7d9a65a7..1b9a1c83 100644
--- a/tests/dataApi/createFolder-test.js
+++ b/tests/dataApi/createFolder-test.js
@@ -33,7 +33,7 @@ test.serial('Create a folder', (t) => {
     })
     .then(function assert (data) {
       t.true(_.find(data.storage.folders, input) != null)
-      let jsonData = CSON.readFileSync(path.join(data.storage.path, 'boostnote.json'))
+      const jsonData = CSON.readFileSync(path.join(data.storage.path, 'boostnote.json'))
       console.log(path.join(data.storage.path, 'boostnote.json'))
       t.true(_.find(jsonData.folders, input) != null)
     })
diff --git a/tests/dataApi/createNote-test.js b/tests/dataApi/createNote-test.js
index 5c31574e..47446aab 100644
--- a/tests/dataApi/createNote-test.js
+++ b/tests/dataApi/createNote-test.js
@@ -54,11 +54,11 @@ test.serial('Create a note', (t) => {
       ])
     })
     .then(function assert (data) {
-      let data1 = data[0]
-      let data2 = data[1]
+      const data1 = data[0]
+      const data2 = data[1]
 
       t.is(storageKey, data1.storage)
-      let jsonData1 = CSON.readFileSync(path.join(storagePath, 'notes', data1.key + '.cson'))
+      const jsonData1 = CSON.readFileSync(path.join(storagePath, 'notes', data1.key + '.cson'))
       t.is(input1.title, data1.title)
       t.is(input1.title, jsonData1.title)
       t.is(input1.description, data1.description)
@@ -73,7 +73,7 @@ test.serial('Create a note', (t) => {
       t.is(input1.snippets[0].name, jsonData1.snippets[0].name)
 
       t.is(storageKey, data2.storage)
-      let jsonData2 = CSON.readFileSync(path.join(storagePath, 'notes', data2.key + '.cson'))
+      const jsonData2 = CSON.readFileSync(path.join(storagePath, 'notes', data2.key + '.cson'))
       t.is(input2.title, data2.title)
       t.is(input2.title, jsonData2.title)
       t.is(input2.content, data2.content)
diff --git a/tests/dataApi/deleteFolder-test.js b/tests/dataApi/deleteFolder-test.js
index 4adf38e1..1d9c7646 100644
--- a/tests/dataApi/deleteFolder-test.js
+++ b/tests/dataApi/deleteFolder-test.js
@@ -31,10 +31,10 @@ test.serial('Delete a folder', (t) => {
     })
     .then(function assert (data) {
       t.true(_.find(data.storage.folders, {key: folderKey}) == null)
-      let jsonData = CSON.readFileSync(path.join(data.storage.path, 'boostnote.json'))
+      const jsonData = CSON.readFileSync(path.join(data.storage.path, 'boostnote.json'))
 
       t.true(_.find(jsonData.folders, {key: folderKey}) == null)
-      let notePaths = sander.readdirSync(data.storage.path, 'notes')
+      const notePaths = sander.readdirSync(data.storage.path, 'notes')
       t.is(notePaths.length, t.context.storage.notes.filter((note) => note.folder !== folderKey).length)
     })
 })
diff --git a/tests/dataApi/migrateFromV6Storage-test.js b/tests/dataApi/migrateFromV6Storage-test.js
index 220289c6..7cdcdb71 100644
--- a/tests/dataApi/migrateFromV6Storage-test.js
+++ b/tests/dataApi/migrateFromV6Storage-test.js
@@ -17,7 +17,7 @@ const os = require('os')
 const dummyStoragePath = path.join(os.tmpdir(), 'test/migrate-test-storage')
 
 test.beforeEach((t) => {
-  let dummyData = t.context.dummyData = TestDummy.dummyLegacyStorage(dummyStoragePath)
+  const dummyData = t.context.dummyData = TestDummy.dummyLegacyStorage(dummyStoragePath)
   console.log('init count', dummyData.notes.length)
   localStorage.setItem('storages', JSON.stringify([dummyData.cache]))
 })
@@ -32,11 +32,11 @@ test.serial('Migrate legacy storage into v1 storage', (t) => {
       t.true(data)
 
       // Check all notes migrated.
-      let dummyData = t.context.dummyData
-      let noteDirPath = path.join(dummyStoragePath, 'notes')
-      let fileList = sander.readdirSync(noteDirPath)
+      const dummyData = t.context.dummyData
+      const noteDirPath = path.join(dummyStoragePath, 'notes')
+      const fileList = sander.readdirSync(noteDirPath)
       t.is(dummyData.notes.length, fileList.length)
-      let noteMap = fileList
+      const noteMap = fileList
         .map((filePath) => {
           return CSON.readFileSync(path.join(noteDirPath, filePath))
         })
diff --git a/tests/dataApi/moveNote-test.js b/tests/dataApi/moveNote-test.js
index 4c31ddca..3fe31c58 100644
--- a/tests/dataApi/moveNote-test.js
+++ b/tests/dataApi/moveNote-test.js
@@ -38,15 +38,15 @@ test.serial('Move a note', (t) => {
       ])
     })
     .then(function assert (data) {
-      let data1 = data[0]
-      let data2 = data[1]
+      const data1 = data[0]
+      const data2 = data[1]
 
-      let jsonData1 = CSON.readFileSync(path.join(storagePath, 'notes', data1.key + '.cson'))
+      const jsonData1 = CSON.readFileSync(path.join(storagePath, 'notes', data1.key + '.cson'))
 
       t.is(jsonData1.folder, folderKey1)
       t.is(jsonData1.title, note1.title)
 
-      let jsonData2 = CSON.readFileSync(path.join(storagePath2, 'notes', data2.key + '.cson'))
+      const jsonData2 = CSON.readFileSync(path.join(storagePath2, 'notes', data2.key + '.cson'))
       t.is(jsonData2.folder, folderKey2)
       t.is(jsonData2.title, note2.title)
       try {
diff --git a/tests/dataApi/renameStorage-test.js b/tests/dataApi/renameStorage-test.js
index b898d6f1..f5c64cb6 100644
--- a/tests/dataApi/renameStorage-test.js
+++ b/tests/dataApi/renameStorage-test.js
@@ -27,7 +27,7 @@ test.serial('Rename a storage', (t) => {
       return renameStorage(storageKey, 'changed')
     })
     .then(function assert (data) {
-      let cachedStorageList = JSON.parse(localStorage.getItem('storages'))
+      const cachedStorageList = JSON.parse(localStorage.getItem('storages'))
       t.true(_.find(cachedStorageList, {key: storageKey}).name === 'changed')
     })
 })
diff --git a/tests/dataApi/reorderFolder-test.js b/tests/dataApi/reorderFolder-test.js
index bb7f6b0c..55bff0eb 100644
--- a/tests/dataApi/reorderFolder-test.js
+++ b/tests/dataApi/reorderFolder-test.js
@@ -34,8 +34,7 @@ test.serial('Reorder a folder', (t) => {
       t.true(_.nth(data.storage.folders, 0).key === secondFolderKey)
       t.true(_.nth(data.storage.folders, 1).key === firstFolderKey)
 
-      let jsonData = CSON.readFileSync(path.join(data.storage.path, 'boostnote.json'))
-      console.log(path.join(data.storage.path, 'boostnote.json'))
+      const jsonData = CSON.readFileSync(path.join(data.storage.path, 'boostnote.json'))
 
       t.true(_.nth(jsonData.folders, 0).key === secondFolderKey)
       t.true(_.nth(jsonData.folders, 1).key === firstFolderKey)
diff --git a/tests/dataApi/updateFolder-test.js b/tests/dataApi/updateFolder-test.js
index ad486344..ca9fcf99 100644
--- a/tests/dataApi/updateFolder-test.js
+++ b/tests/dataApi/updateFolder-test.js
@@ -34,7 +34,7 @@ test.serial('Update a folder', (t) => {
     })
     .then(function assert (data) {
       t.true(_.find(data.storage.folders, input) != null)
-      let jsonData = CSON.readFileSync(path.join(data.storage.path, 'boostnote.json'))
+      const jsonData = CSON.readFileSync(path.join(data.storage.path, 'boostnote.json'))
       console.log(path.join(data.storage.path, 'boostnote.json'))
       t.true(_.find(jsonData.folders, input) != null)
     })
diff --git a/tests/dataApi/updateNote-test.js b/tests/dataApi/updateNote-test.js
index 2c6aad9c..6043ee1e 100644
--- a/tests/dataApi/updateNote-test.js
+++ b/tests/dataApi/updateNote-test.js
@@ -74,8 +74,8 @@ test.serial('Update a note', (t) => {
           createNote(storageKey, input2)
         ])
         .then(function updateNotes (data) {
-          let data1 = data[0]
-          let data2 = data[1]
+          const data1 = data[0]
+          const data2 = data[1]
           return Promise.all([
             updateNote(data1.storage, data1.key, input3),
             updateNote(data1.storage, data2.key, input4)
@@ -83,10 +83,10 @@ test.serial('Update a note', (t) => {
         })
     })
     .then(function assert (data) {
-      let data1 = data[0]
-      let data2 = data[1]
+      const data1 = data[0]
+      const data2 = data[1]
 
-      let jsonData1 = CSON.readFileSync(path.join(storagePath, 'notes', data1.key + '.cson'))
+      const jsonData1 = CSON.readFileSync(path.join(storagePath, 'notes', data1.key + '.cson'))
       t.is(input3.title, data1.title)
       t.is(input3.title, jsonData1.title)
       t.is(input3.description, data1.description)
@@ -100,7 +100,7 @@ test.serial('Update a note', (t) => {
       t.is(input3.snippets[0].name, data1.snippets[0].name)
       t.is(input3.snippets[0].name, jsonData1.snippets[0].name)
 
-      let jsonData2 = CSON.readFileSync(path.join(storagePath, 'notes', data2.key + '.cson'))
+      const jsonData2 = CSON.readFileSync(path.join(storagePath, 'notes', data2.key + '.cson'))
       t.is(input4.title, data2.title)
       t.is(input4.title, jsonData2.title)
       t.is(input4.content, data2.content)