Refactor markdown rendering into separate module

lib/core/Remarkable.js

@@ -1,47 +1,25 @@
 'use strict';
 
 const React = require('react');
-const hljs = require('highlight.js');
-const Markdown = require('remarkable');
-const toSlug = require('./toSlug.js');
+const renderMarkdown = require('./renderMarkdown.js');
 
 const CWD = process.cwd();
 
-/**
- * The anchors plugin adds GFM-style anchors to headings.
- */
-function anchors(md) {
-  md.renderer.rules.heading_open = function(tokens, idx /*, options, env */) {
-    const textToken = tokens[idx + 1];
-    return (
-      '<h' +
-      tokens[idx].hLevel +
-      '><a class="anchor" aria-hidden="true" name="' +
-      toSlug(textToken.content) +
-      '"></a><a href="#' +
-      toSlug(textToken.content) +
-      '" aria-hidden="true" class="hash-link" ><svg aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>'
-    );
-  };
-}
-
 class Remarkable extends React.Component {
   content() {
     if (this.props.source) {
       return (
         <span
           dangerouslySetInnerHTML={{
-            __html: this.renderMarkdown(this.props.source),
+            __html: renderMarkdown(this.props.source),
           }}
         />
       );
     } else {
       return React.Children.map(this.props.children, child => {
         if (typeof child === 'string') {
           return (
-            <span
-              dangerouslySetInnerHTML={{__html: this.renderMarkdown(child)}}
-            />
+            <span dangerouslySetInnerHTML={{__html: renderMarkdown(child)}} />
           );
         } else {
           return child;
@@ -50,50 +28,6 @@ class Remarkable extends React.Component {
     }
   }
 
-  renderMarkdown(source) {
-    if (!this.md) {
-      const siteConfig = require(CWD + '/siteConfig.js');
-
-      this.md = new Markdown({
-        // Highlight.js expects hljs css classes on the code element.
-        // This results in <pre><code class="hljs css javascript">
-        langPrefix: 'hljs css ',
-        highlight: function(str, lang) {
-          lang =
-            lang || (siteConfig.highlight && siteConfig.highlight.defaultLang);
-          if (lang && hljs.getLanguage(lang)) {
-            try {
-              return hljs.highlight(lang, str).value;
-            } catch (err) {}
-          }
-
-          try {
-            return hljs.highlightAuto(str).value;
-          } catch (err) {}
-
-          return '';
-        },
-        html: true,
-        linkify: true,
-      });
-
-      // Register anchors plugin
-      this.md.use(anchors);
-
-      // Allow client sites to register their own plugins
-      if (siteConfig.markdownPlugins) {
-        siteConfig.markdownPlugins.forEach(function(plugin) {
-          this.md.use(plugin);
-        }, this);
-      }
-    }
-    const html = this.md.render(source);
-
-    // Ensure fenced code blocks use Highlight.js hljs class
-    // https://github.com/jonschlinkert/remarkable/issues/224
-    return html.replace(/<pre><code>/g, '<pre><code class="hljs">');
-  }
-
   render() {
     var Container = this.props.container;
 

lib/core/renderMarkdown.js

@@ -0,0 +1,85 @@
+/**
+ * Copyright (c) 2017-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+const hljs = require('highlight.js');
+const Markdown = require('remarkable');
+const toSlug = require('./toSlug.js');
+
+const CWD = process.cwd();
+
+/**
+ * The anchors plugin adds GFM-style anchors to headings.
+ */
+function anchors(md) {
+  md.renderer.rules.heading_open = function(tokens, idx /*, options, env */) {
+    const textToken = tokens[idx + 1];
+    return (
+      '<h' +
+      tokens[idx].hLevel +
+      '><a class="anchor" aria-hidden="true" name="' +
+      toSlug(textToken.content) +
+      '"></a><a href="#' +
+      toSlug(textToken.content) +
+      '" aria-hidden="true" class="hash-link" ><svg aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>'
+    );
+  };
+}
+
+class MarkdownRenderer {
+  constructor() {
+    const siteConfig = require(CWD + '/siteConfig.js');
+
+    const md = new Markdown({
+      // Highlight.js expects hljs css classes on the code element.
+      // This results in <pre><code class="hljs css javascript">
+      langPrefix: 'hljs css ',
+      highlight: function(str, lang) {
+        lang =
+          lang || (siteConfig.highlight && siteConfig.highlight.defaultLang);
+        if (lang && hljs.getLanguage(lang)) {
+          try {
+            return hljs.highlight(lang, str).value;
+          } catch (err) {}
+        }
+
+        try {
+          return hljs.highlightAuto(str).value;
+        } catch (err) {}
+
+        return '';
+      },
+      html: true,
+      linkify: true,
+    });
+
+    // Register anchors plugin
+    md.use(anchors);
+
+    // Allow client sites to register their own plugins
+    if (siteConfig.markdownPlugins) {
+      siteConfig.markdownPlugins.forEach(function(plugin) {
+        md.use(plugin);
+      });
+    }
+
+    this._md = md;
+  }
+
+  toHtml(source) {
+    const html = this._md.render(source);
+
+    // Ensure fenced code blocks use Highlight.js hljs class
+    // https://github.com/jonschlinkert/remarkable/issues/224
+    return html.replace(/<pre><code>/g, '<pre><code class="hljs">');
+  }
+}
+
+const renderMarkdown = new MarkdownRenderer();
+
+module.exports = source => {
+  return renderMarkdown.toHtml(source);
+};