复制代码 代码如下:
var PeriodicalExecuter = Class.create();
PeriodicalExecuter.prototype = {
initialize: function(callback, frequency) {
this.callback = callback;
this.frequency = frequency;
this.currentlyExecuting = false;
this.registerCallback();
},
registerCallback: function() {
setTimeout(this.onTimerEvent.bind(this), this.frequency * 1000);
},
onTimerEvent: function() {
if (!this.currentlyExecuting) {
try {
this.currentlyExecuting = true;
this.callback();
} finally {
this.currentlyExecuting = false;
}
}
this.registerCallback();
}
}
具体Class.create()背后做了什么，具体来看看Class的实现。
复制代码 代码如下:
var Class = {
create: function() {
return function() {
this.initialize.apply(this, arguments);
}
}
}
Class.create实际上是返回一个函数，那么new的时候，做了些什么呢。参照MDN
When the code new foo(...) is executed, the following things happen:
A new object is created, inheriting from foo.prototype.
The constructor function foo is called with the specified arguments and this bound to the newly created object. new foo is equivalent to new foo(), i.e. if no argument list is specified, foo is called without arguments.
The object returned by the constructor function becomes the result of the whole new expression. If the constructor function doesn't explicitly return an object, the object created in step 1 is used instead. (Normally constructors don't return a value, but they can choose to do so if they want to override the normal object creation process.)
new的时候会执行该返回的函数，即执行this.initialize.apply(this, arguments); 此时的this就是新生成的对象，这也就是说了所有对象的初始化工作全部委托给initialize函数了。
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这里为什么要把自己的initialize方法绑定到自己身上？？
