use e instead of event variable name

app/assets/javascripts/diff.js.es6

@@ -20,8 +20,8 @@
       this.highlighSelectedLine();
     }
 
-    handleClickUnfold(event) {
-      const $target = $(event.target);
+    handleClickUnfold(e) {
+      const $target = $(e.target);
       // current babel config relies on iterators implementation, so we cannot simply do:
       // const [oldLineNumber, newLineNumber] = this.lineNumbers($target.parent());
       const ref = this.lineNumbers($target.parent());
@@ -69,9 +69,9 @@
       }
     }
 
-    handleClickLineNum(event) {
-      const hash = $(event.currentTarget).attr('href');
-      event.preventDefault();
+    handleClickLineNum(e) {
+      const hash = $(e.currentTarget).attr('href');
+      e.preventDefault();
       if (window.history.pushState) {
         window.history.pushState(null, null, hash);
       } else {

app/assets/javascripts/merge_request_tabs.js.es6

@@ -91,13 +91,13 @@
         .off('click', '.js-show-tab', this.showTab);
     }
 
-    showTab(event) {
-      event.preventDefault();
-      this.activateTab($(event.target).data('action'));
+    showTab(e) {
+      e.preventDefault();
+      this.activateTab($(e.target).data('action'));
     }
 
-    tabShown(event) {
-      const $target = $(event.target);
+    tabShown(e) {
+      const $target = $(e.target);
       const action = $target.data('action');
 
       if (action === 'commits') {