migrate balsamiq_viewer to dynamic import

app/assets/javascripts/blob/balsamiq_viewer.js

@@ -7,7 +7,7 @@ function onError() {
   return flash;
 }
 
-function loadBalsamiqFile() {
+export default function loadBalsamiqFile() {
   const viewer = document.getElementById('js-balsamiq-viewer');
 
   if (!(viewer instanceof Element)) return;
@@ -17,5 +17,3 @@ function loadBalsamiqFile() {
   const balsamiqViewer = new BalsamiqViewer(viewer);
   balsamiqViewer.loadFile(endpoint).catch(onError);
 }
-
-$(loadBalsamiqFile);

app/assets/javascripts/blob/viewer/index.js

@@ -5,6 +5,7 @@ import axios from '../../lib/utils/axios_utils';
 export default class BlobViewer {
   constructor() {
     BlobViewer.initAuxiliaryViewer();
+    BlobViewer.initRichViewer();
 
     this.initMainViewers();
   }
@@ -16,6 +17,26 @@ export default class BlobViewer {
     BlobViewer.loadViewer(auxiliaryViewer);
   }
 
+  static initRichViewer() {
+    const viewer = document.querySelector('.blob-viewer[data-type="rich"]');
+    if (!viewer || !viewer.dataset.richType) return;
+
+    const initViewer = promise => promise
+      .then(module => module.default(viewer))
+      .catch((error) => {
+        Flash('Error loading file viewer.');
+        throw error;
+      });
+
+    switch (viewer.dataset.richType) {
+      case 'balsamiq':
+        initViewer(import(/* webpackChunkName: 'balsamiq_viewer' */ '../balsamiq_viewer'));
+        break;
+      default:
+        break;
+    }
+  }
+
   initMainViewers() {
     this.$fileHolder = $('.file-holder');
     if (!this.$fileHolder.length) return;

app/views/projects/blob/_viewer.html.haml

 - hidden = local_assigns.fetch(:hidden, false)
 - render_error = viewer.render_error
+- rich_type = viewer.type == :rich ? viewer.partial_name : nil
 - load_async = local_assigns.fetch(:load_async, viewer.load_async? && render_error.nil?)
 
 - viewer_url = local_assigns.fetch(:viewer_url) { url_for(params.merge(viewer: viewer.type, format: :json)) } if load_async
-.blob-viewer{ data: { type: viewer.type, url: viewer_url }, class: ('hidden' if hidden) }
+.blob-viewer{ data: { type: viewer.type, rich_type: rich_type, url: viewer_url }, class: ('hidden' if hidden) }
   - if render_error
     = render 'projects/blob/render_error', viewer: viewer
   - elsif load_async

app/views/projects/blob/viewers/_balsamiq.html.haml

-- content_for :page_specific_javascripts do
-  = webpack_bundle_tag('balsamiq_viewer')
-
 .file-content.balsamiq-viewer#js-balsamiq-viewer{ data: { endpoint: blob_raw_path } }

config/webpack.config.js

@@ -48,7 +48,6 @@ function generateEntries() {
   autoEntriesCount = Object.keys(autoEntries).length;
 
   const manualEntries = {
-    balsamiq_viewer:      './blob/balsamiq_viewer.js',
     monitoring:           './monitoring/monitoring_bundle.js',
     mr_notes:             './mr_notes/index.js',
     notebook_viewer:      './blob/notebook_viewer.js',