From 7151015a49063a694df6563a7bce4ac3c10b45d2 Mon Sep 17 00:00:00 2001
From: Clemens Wolff <clewolff@microsoft.com>
Date: Fri, 24 May 2019 10:07:37 -0400
Subject: [PATCH] Exclude unused hljs languages from bundle

---
 app/server/static/components/hljsLanguages.js |  1 +
 app/server/static/components/uploadMixin.js   | 10 +++++++++-
 app/server/static/webpack.config.js           |  6 ++++++
 3 files changed, 16 insertions(+), 1 deletion(-)
 create mode 100644 app/server/static/components/hljsLanguages.js

diff --git a/app/server/static/components/hljsLanguages.js b/app/server/static/components/hljsLanguages.js
new file mode 100644
index 00000000..dd98ba87
--- /dev/null
+++ b/app/server/static/components/hljsLanguages.js
@@ -0,0 +1 @@
+module.exports = ['json'];
diff --git a/app/server/static/components/uploadMixin.js b/app/server/static/components/uploadMixin.js
index 1ccb6156..d0af074e 100644
--- a/app/server/static/components/uploadMixin.js
+++ b/app/server/static/components/uploadMixin.js
@@ -1,7 +1,15 @@
-import hljs from 'highlight.js';
+import hljs from 'highlight.js/lib/highlight';
+import hljsLanguages from './hljsLanguages';
 import HTTP, { newHttpClient } from './http';
 import Messages from './messages.vue';
 
+hljsLanguages.forEach((languageName) => {
+  /* eslint-disable import/no-dynamic-require, global-require */
+  const languageModule = require(`highlight.js/lib/languages/${languageName}`);
+  /* eslint-enable import/no-dynamic-require, global-require */
+  hljs.registerLanguage(languageName, languageModule);
+});
+
 export default {
   components: { Messages },
 
diff --git a/app/server/static/webpack.config.js b/app/server/static/webpack.config.js
index fbf636bd..d6d41bad 100644
--- a/app/server/static/webpack.config.js
+++ b/app/server/static/webpack.config.js
@@ -3,6 +3,8 @@ const path = require('path');
 const process = require('process');
 const BundleTracker = require('webpack-bundle-tracker');
 const VueLoaderPlugin = require('vue-loader/lib/plugin')
+const { ContextReplacementPlugin } = require('webpack');
+const hljsLanguages = require('./components/hljsLanguages');
 
 const devMode = process.env.DEBUG !== 'False';
 const hotReload = process.env.HOT_RELOAD === '1';
@@ -58,6 +60,10 @@ module.exports = {
         ]
     },
     plugins: [
+        new ContextReplacementPlugin(
+            /highlight\.js\/lib\/languages$/,
+            new RegExp(`^./(${hljsLanguages.join('|')})$`)
+        ),
         new BundleTracker({ filename: './webpack-stats.json' }),
         new VueLoaderPlugin()
     ],