Merge pull request #87 from teddyzeenny/fix-leak

Fix memory leak caused by the click event listener

app/instance-initializers/ember-href-to.js

@@ -1,6 +1,5 @@
 import HrefTo from 'ember-href-to/href-to';
 
-let hrefToClickHandler;
 function closestLink(el) {
   if (el.closest) {
     return el.closest('a');
@@ -17,11 +16,7 @@ export default {
   initialize(applicationInstance) {
     // we only want this to run in the browser, not in fastboot
     if (typeof(FastBoot) === "undefined") {
-      if (hrefToClickHandler !== undefined) {
-        document.body.removeEventListener('click', hrefToClickHandler);
-      }
-
-      hrefToClickHandler = function _hrefToClickHandler(e) {
+      let hrefToClickHandler = function _hrefToClickHandler(e) {
         let link = e.target.tagName === 'A' ? e.target : closestLink(e.target);
         if (link) {
           let hrefTo = new HrefTo(applicationInstance, e, link);
@@ -30,6 +25,15 @@ export default {
       };
 
       document.body.addEventListener('click', hrefToClickHandler);
+
+      // Teardown on app destruction: clean up the event listener to avoid
+      // memory leaks.
+      applicationInstance.reopen({
+        willDestroy() {
+          document.body.removeEventListener('click', hrefToClickHandler);
+          return this._super(...arguments);
+        }
+      });
     }
   }
 };

tests/acceptance/href-to-test.js

@@ -1,6 +1,7 @@
 import { test } from 'qunit';
 import moduleForAcceptance from '../../tests/helpers/module-for-acceptance';
 import $ from 'jquery';
+import destroyApp from '../../tests/helpers/destroy-app';
 
 function leftClick(selector) {
   triggerEvent(selector, 'click', { which: 1 });
@@ -122,3 +123,25 @@ test('[BUGFIX] it works with the `click` acceptance helper', function(assert) {
     assertAnchorIsActive('#link-to-links a:contains(About)', assert);
   });
 });
+
+test('The event listener does\'nt leak after the app is destroyed', function(assert) {
+  // Boot the app
+  visit('/');
+
+  andThen(app => {
+    // Destroy the app
+    destroyApp(app);
+    // Prevent an actual redirect if the test fails (when an error occurs
+    // inside an event handler `preventDefault()` never happens therefore
+    // causing an actual redirect).
+    let preventDefault = e => e.preventDefault();
+    document.body.addEventListener('click', preventDefault);
+
+    // Click on a link with a recognizable URL
+    let a = $('<a href="/about">').appendTo('body')[0].click();
+    assert.ok(true, 'no errors thrown due to attempting to handle a URL in a destroyed application');
+
+    $(a).remove();
+    document.body.removeEventListener('click', preventDefault);
+  });
+});