refactor(animationFrame): simplify requestAnimationFrame logic

spec/helpers/testScheduler-ui.ts

@@ -12,6 +12,42 @@ const commonInterface = require('mocha/lib/interfaces/common');
 const escapeRe = require('escape-string-regexp');
 //tslint:enable:no-var-requires no-require-imports
 
+/** Polyfill requestAnimationFrame for testing animationFrame scheduler in Node */
+// http://paulirish.com/2011/requestanimationframe-for-smart-animating/
+// http://my.opera.com/emoller/blog/2011/12/20/requestanimationframe-for-smart-er-animating
+
+// requestAnimationFrame polyfill by Erik Möller. fixes from Paul Irish and Tino Zijdel
+
+// MIT license
+
+(function(this: any, window: any) {
+  window = window || this;
+  let lastTime = 0;
+  const vendors = ['ms', 'moz', 'webkit', 'o'];
+  for (let x = 0; x < vendors.length && !window.requestAnimationFrame; ++x) {
+      window.requestAnimationFrame = window[vendors[x] + 'RequestAnimationFrame'];
+      window.cancelAnimationFrame = window[vendors[x] + 'CancelAnimationFrame']
+                                 || window[vendors[x] + 'CancelRequestAnimationFrame'];
+  }
+
+  if (!window.requestAnimationFrame) {
+      window.requestAnimationFrame = (callback: Function, element: any) => {
+          const currTime = new Date().getTime();
+          const timeToCall = Math.max(0, 16 - (currTime - lastTime));
+          const id = window.setTimeout(() => { callback(currTime + timeToCall); },
+            timeToCall);
+          lastTime = currTime + timeToCall;
+          return id;
+      };
+  }
+
+  if (!window.cancelAnimationFrame) {
+      window.cancelAnimationFrame = (id: number) => {
+          clearTimeout(id);
+      };
+  }
+}(global));
+
 //setup sinon-chai
 chai.use(sinonChai);
 

src/internal/scheduler/AnimationFrameAction.ts

@@ -1,5 +1,4 @@
 import { AsyncAction } from './AsyncAction';
-import { AnimationFrame } from '../util/AnimationFrame';
 import { AnimationFrameScheduler } from './AnimationFrameScheduler';
 import { Action } from './Action';
 
@@ -25,7 +24,7 @@ export class AnimationFrameAction<T> extends AsyncAction<T> {
     // If an animation frame has already been requested, don't request another
     // one. If an animation frame hasn't been requested yet, request one. Return
     // the current animation frame request id.
-    return scheduler.scheduled || (scheduler.scheduled = AnimationFrame.requestAnimationFrame(
+    return scheduler.scheduled || (scheduler.scheduled = requestAnimationFrame(
       () => scheduler.flush(null)));
   }
   protected recycleAsyncId(scheduler: AnimationFrameScheduler, id?: any, delay: number = 0): any {
@@ -39,7 +38,7 @@ export class AnimationFrameAction<T> extends AsyncAction<T> {
     // set the scheduled flag to undefined so the next AnimationFrameAction will
     // request its own.
     if (scheduler.actions.length === 0) {
-      AnimationFrame.cancelAnimationFrame(id);
+      cancelAnimationFrame(id);
       scheduler.scheduled = undefined;
     }
     // Return undefined so the action knows to request a new async id if it's rescheduled.