调用方法形式setInterval()导致异常

Question

我想从setInterval()调用函数.这是一个想法:

class Greeter {
    element: HTMLElement;
    span: HTMLElement;
    timerToken: number;

    constructor(element: HTMLElement) {
        this.element = element;
        this.element.innerHTML += "The time is: ";
        this.span = document.createElement('span');
        this.element.appendChild(this.span);
        this.span.innerText = new Date().toUTCString();
        //this.element.style.cssText = "-webkit-transform:rotate(7deg)";     
        //this.element.style.transition = "-webkit-transform: rotate(180deg)";         
    }

    start() {
        this.timerToken = setInterval(this.runningLoop(this.element), 500);        
    }

    stop() {
        clearTimeout(this.timerToken);
    }

    runningLoop(element: HTMLElement) {
        this.element.style.cssText = "-webkit-transform:rotate(7deg)";         
    }


}

window.onload = () => {
    var el = document.getElementById('content');
    var greeter = new Greeter(el);

    greeter.start();
};        

在这种情况下,我得到一个例外:

第13行第9列的未处理异常.Microsoft JScript运行时错误:参数无效.

所以我尝试如下:

this.timerToken = setInterval(function () { this.runningLoop(this.element) }.bind, 500);

没有例外但没有任何反应..

有任何想法吗 ？

Answer 1

setInterval(this.runningLoop(this.element), 500);

以上this.runningLoop在传递给它之前调用setInterval,setInterval期待一个函数但是正在接收undefined.用箭头功能包裹呼叫......

setInterval(() => this.runningLoop(this.element), 500);

既然你没有使用元素参数runningLoop,你可以删除参数并将方法传递给setInterval...

setInterval(this.runningLoop, 500);