var AnimationManager = function (time, completionMethod) {
"use strict";
this.animationObjects = [];
this.time = time;
this.add = function (animationObject) {
this.animationObjects.push(animationObject);
};
this.completionMethod = completionMethod;
this.currentStage = 0;
this.maximumStage = this.time * FPS;
this.tick = function () {
this.currentStage += 1;
var i;
for (i = 0; i < this.animationObjects.length; i += 1) {
this.animationObjects[i].applyAnimation(this.currentStage);
}
if (this.currentStage < this.maximumStage) {
console.log(this.currentStage);
setTimeout(this.tick, 1000.0 / FPS);
} else {
this.completionMethod();
}
};
//Call this to start
this.startAnimation = function () {
this.timer = setTimeout(this.tick, 1000.0 / FPS);
};
};
chrome控制台说这个.animationObjects是未定义的,但我把它设置为一个空数组。这是为什么?
答案 0 :(得分:3)
当您将其作为超时处理程序传递时,this.tick
的上下文将丢失。使用:
this.timer = setTimeout(this.tick.bind(this), 1000.0 / FPS);
或略显老气:
var mgr = this;
this.timer = setTimeout(function() { mgr.tick(); }, 1000.0 / FPS);
this
的值是在每次调用函数时确定的。函数与任何特定对象之间没有固有的长期关系;换句话说,“tick”函数最初创建为该对象的属性值的事实确实无关紧要。重要的是该函数是如何被称为。