setTimeout(myFunction, 5000);vs setTimeout(myFunction(), 5000); [英] setTimeout(myFunction, 5000); vs setTimeout(myFunction(), 5000);

问题描述

我在玩setTimeout"函数.此代码按预期运行:

I was playing around with the "setTimeout" function. This code runs like expected:

function myFunction() {
    console.log('test');
    setTimeout(myFunction, 1000);
}
myFunction();

它每秒向控制台打印一次测试".

It prints every second 'test' to the console.

但是当运行此代码时，超时不会等待:

But when running this code the timeout is not waiting:

function myFunction() {
    console.log('test');
    setTimeout(myFunction(), 1000);
}
myFunction();

它用测试"向我的控制台发送垃圾邮件.

And it spams my console with 'test'.

代码中唯一的区别是 myFunction() 调用的括号.为什么会这样?

The only difference in code are the brackets of myFunction() call. Why is this happening?

推荐答案

myFunction()立即调用函数并将其返回值传递给setTimeoutcode> 稍后调用(除了它的返回值是 undefined，它不是一个函数(或字符串)，所以没有意义).

myFunction() calls the function immediately and passes its return value to setTimeout to be called later (except its return value is undefined, which isn't a function (or a string), so that is pointless).

这篇关于setTimeout(myFunction, 5000);vs setTimeout(myFunction(), 5000);的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！