Little refactoring to avoid circular execution when listing for dom mutations (OctoLinker#514)

stefanbuck · web-flow · commit dea569c6ebaa · 2018-09-15T00:20:13.000+02:00
For some reason the following PR microdevs/missy#39 causes the browser hang when trying to add a inline comment. I tested the same functionally on a few other PRs and it worked fine for all of them. However, I was able to narrow it down to the `MutationObserver` which is called over and over again. I have no idea what is different there, but I decided to rewrite the related code to only spy for dom mutations when expanding the blob.
diff --git a/packages/core/octo-linker.js b/packages/core/octo-linker.js
@@ -1,3 +1,4 @@
+import $ from 'jquery';
 import injection from 'github-injection';
 import BlobReader from '@octolinker/blob-reader';
 import insertLink from '@octolinker/helper-insert-link';
@@ -65,14 +66,14 @@ async function run(self) {
   clickHandler(matches);
 }
 
-function observeExpand(self) {
-  const observer = new MutationObserver(() => {
-    run(self);
+function waitFor(el, cb) {
+  const viewSpy = new MutationObserver(() => {
+    cb();
   });
 
-  for (const el of document.querySelectorAll('.diff-table tbody')) {
-    observer.observe(el, { childList: true });
-  }
+  viewSpy.observe(el, {
+    childList: true,
+  });
 }
 
 export default class OctoLinkerCore {
@@ -82,6 +83,9 @@ export default class OctoLinkerCore {
 
   init() {
     injection(run.bind(null, this));
-    observeExpand(this);
+
+    $('.js-expand').on('click', event => {
+      waitFor($(event.target).closest('tbody')[0], run.bind(null, this));
+    });
   }
 }
