Typescript 中的 setInterval 和 setTimeout [英] setInterval and setTimeout in Typescript

问题描述

我正在学习 Typescript，并尝试在一段时间内多次打印控制台消息.但在我的测试中，这种情况发生过一次，你知道原因吗?

I am learning Typescript and am trying to print a console message a number of times over a period of time. But in my test this happens once, you know the reason?

代码如下:

 class Class {
    private msg: string;
    constructor(msg: string) {
        this.msg = msg;
    }
    private printMsg(): void {
        console.log(this.msg);
    };
    public repeatMsg(): void {
        let intervalo = setInterval(this.printMsg(), 2000);
        setTimeout(function() {
            clearInterval(intervalo);
        }, 40000);
    }
}

let test: Class;
test = new Class("Hello");
test.repeatMsg();

推荐答案

你的代码有问题:

setInterval(this.printMsg(), 2000);

setInterval 接受一个函数作为第一个参数.表达式this.printMsg()是函数的调用，实际上是void.有两种方法可以修复它.使用拉姆达:

setInterval accepts a function as a first parameter. Expression this.printMsg() is a call of the function, and is void actually. There are two ways to fix it. Use lambda:

setInterval(() = > this.printMsg(), 2000);

或者使用绑定:

setInterval(this.printMsg.bind(this), 2000);

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