001 - router-scroll mixin added

addon/mixins/router-scroll.js

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+import Ember from 'ember';
+
+// ember-router-scroll variables
+let popStateEvent = false;
+const scrollMap = {};
+let windowLocation = '';
+
+// ember-router-scroll event handler
+window.addEventListener('popstate', () => {
+  popStateEvent = true;
+});
+
+export default Ember.Mixin.create({
+
+  willTransition(...args) {
+    this._super(...args);
+    scrollMap[windowLocation] = Ember.$(window).scrollTop();
+  },
+
+  didTransition(transitions, ...args) {
+    this._super(transitions, ...args);
+
+    Ember.run.next(() => {
+      windowLocation = window.location.pathname;
+      const scrollPosition = scrollMap[windowLocation] ? scrollMap[windowLocation] : 0;
+      const preserveScrollPosition = transitions[transitions.length - 1]
+        .handler.controller.get('preserveScrollPosition');
+      if (popStateEvent) {
+        // If the back or forward browser button is pressed, set scroll top to
+        // the position it had when the page was last seen.
+        Ember.$(window).scrollTop(scrollPosition);
+      } else {
+        // This is an initial or direct page visit, so begin at page top.
+        if (preserveScrollPosition) {return;}
+        Ember.$(window).scrollTop(0);
+      }
+
+      // Reset popstate event status.
+      popStateEvent = false;
+    });
+  },
+});

app/mixins/ember-router-scroll.js

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+export { default } from 'ember-router-scroll/mixins/router-scroll';

tests/unit/mixins/router-scroll-test.js

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+import Ember from 'ember';
+import RouterScrollMixin from 'ember-router-scroll/mixins/router-scroll';
+import { module, test } from 'qunit';
+
+module('Unit | Mixin | router scroll');
+
+// Replace this with your real tests.
+test('it works', function(assert) {
+  let RouterScrollObject = Ember.Object.extend(RouterScrollMixin);
+  let subject = RouterScrollObject.create();
+  assert.ok(subject);
+});