class Timer {//js 内置的timer对象    private _jsInnerTimerObj: any;    private _enable: boolean;    private _handlerInvoker:any;    private _interval: number;        get Interval(): number{        return this._interval;    }    set Interval(value: number) {        this._interval = value;        //重新设定新的定时器        if (this._jsInnerTimerObj) {            window.clearInterval(this._jsInnerTimerObj);        }                   }    private _elapsed:any;    get Elapsed(): any{        return this._elapsed;    }    set Elapsed(value: any) {        /*if (!isFunction(value)) {            throw new Error("the Elapsed value must be function!");        }*/        this._elapsed = value;        //只有设置了触发事件才定时，没有回调的定时器是无意义的定时执行其中的匿名方法        this._jsInnerTimerObj = window.setInterval(this._handlerInvoker, this.Interval);                     }    /*  构造函数    *@interval 设置定时器的毫秒数    */    constructor(interval: number) {        this._enable = false;        this.Interval = interval;        var that = this;        this._handlerInvoker = function () {             if (that.Elapsed&&that._enable==true){                that.Elapsed();             }        }    }    Start() {        this._enable = true;    }    Stop() {        this._enable = false;    }}var t = new Timer(500);t.Elapsed = function () {   document.write(99)}t.Start();