refactor file structure

browser/lib/markdown.js

@@ -0,0 +1,38 @@
+import markdownit from 'markdown-it'
+import hljs from 'highlight.js'
+import emoji from 'markdown-it-emoji'
+
+var md = markdownit({
+  typographer: true,
+  linkify: true,
+  highlight: function (str, lang) {
+    if (lang && hljs.getLanguage(lang)) {
+      try {
+        return hljs.highlight(lang, str).value
+      } catch (__) {}
+    }
+
+    try {
+      return hljs.highlightAuto(str).value
+    } catch (__) {}
+
+    return ''
+  }
+})
+md.use(emoji)
+
+let originalRenderToken = md.renderer.renderToken
+md.renderer.renderToken = function renderToken (tokens, idx, options) {
+  let token = tokens[idx]
+  let result = originalRenderToken.call(md.renderer, tokens, idx, options)
+  if (token.map != null) {
+    return result + '<a class=\'lineAnchor\' data-key=\'' + token.map[0] + '\'></a>'
+  }
+  return result
+}
+
+export default function markdown (content) {
+  if (content == null) content = ''
+
+  return md.render(content.toString())
+}