re-apply MR !6285 "Added forceLoad ability to singleFileDiffs, added callback...

re-apply MR !6285 "Added forceLoad ability to singleFileDiffs, added callback to getContentHTML, added conditional force load if a collapsed diff line anchor is found"

Use url utility to retrieve hash

app/assets/javascripts/diff.js.es6

@@ -58,6 +58,17 @@
       $.get(link, params, response => $target.parent().replaceWith(response));
     }
 
+    openAnchoredDiff(anchoredDiff, cb) {
+      const diffTitle = $(`#file-path-${anchoredDiff}`);
+      const diffFile = diffTitle.closest('.diff-file');
+      const nothingHereBlock = $('.nothing-here-block:visible', diffFile);
+      if (nothingHereBlock.length) {
+        diffFile.singleFileDiff(true, cb);
+      } else {
+        cb();
+      }
+    }
+
     handleClickLineNum(event) {
       const hash = $(event.currentTarget).attr('href');
       event.preventDefault();

app/assets/javascripts/merge_request_tabs.js.es6

@@ -239,9 +239,14 @@
             this.expandViewContainer();
           }
           this.diffsLoaded = true;
-          this.scrollToElement('#diffs');
 
-          new gl.Diff();
+          const diffPage = new gl.Diff();
+
+          const locationHash = gl.utils.getLocationHash();
+          const anchoredDiff = locationHash && locationHash.split('_')[0];
+          if (anchoredDiff) {
+            diffPage.openAnchoredDiff(anchoredDiff, () => this.scrollToElement('#diffs'));
+          }
         },
       });
     }

app/assets/javascripts/single_file_diff.js

@@ -13,7 +13,8 @@
 
     COLLAPSED_HTML = '<div class="nothing-here-block diff-collapsed">This diff is collapsed. <a class="click-to-expand">Click to expand it.</a></div>';
 
-    function SingleFileDiff(file) {
+    function SingleFileDiff(file, forceLoad, cb) {
+      var clickTarget;
       this.file = file;
       this.toggleDiff = bind(this.toggleDiff, this);
       this.content = $('.diff-content', this.file);
@@ -31,10 +32,13 @@
         this.content.after(this.collapsedContent);
         this.$toggleIcon.addClass('fa-caret-down');
       }
-      $('.file-title, .click-to-expand', this.file).on('click', this.toggleDiff);
+      clickTarget = $('.file-title, .click-to-expand', this.file).on('click', this.toggleDiff);
+      if (forceLoad) {
+        this.toggleDiff({ target: clickTarget }, cb);
+      }
     }
 
-    SingleFileDiff.prototype.toggleDiff = function(e) {
+    SingleFileDiff.prototype.toggleDiff = function(e, cb) {
       var $target = $(e.target);
       if (!$target.hasClass('file-title') && !$target.hasClass('click-to-expand') && !$target.hasClass('diff-toggle-caret')) return;
       this.isOpen = !this.isOpen;
@@ -54,11 +58,11 @@
         }
       } else {
         this.$toggleIcon.addClass('fa-caret-down').removeClass('fa-caret-right');
-        return this.getContentHTML();
+        return this.getContentHTML(cb);
       }
     };
 
-    SingleFileDiff.prototype.getContentHTML = function() {
+    SingleFileDiff.prototype.getContentHTML = function(cb) {
       this.collapsedContent.hide();
       this.loadingContent.show();
       $.get(this.diffForPath, (function(_this) {
@@ -76,6 +80,8 @@
           if (typeof gl.diffNotesCompileComponents !== 'undefined') {
             gl.diffNotesCompileComponents();
           }
+
+          if (cb) cb();
         };
       })(this));
     };
@@ -84,10 +90,10 @@
 
   })();
 
-  $.fn.singleFileDiff = function() {
+  $.fn.singleFileDiff = function(forceLoad, cb) {
     return this.each(function() {
-      if (!$.data(this, 'singleFileDiff')) {
-        return $.data(this, 'singleFileDiff', new SingleFileDiff(this));
+      if (!$.data(this, 'singleFileDiff') || forceLoad) {
+        return $.data(this, 'singleFileDiff', new SingleFileDiff(this, forceLoad, cb));
       }
     });
   };