不带箭头功能的setInterval函数 [英] setInterval function without arrow function

问题描述

我正在根据文档 https://facebook了解关于React组件的信息.github.io/react/docs/state-and-lifecycle.html

为什么我们需要在这里使用箭头功能:

Why do we need to use arrow function here:

this.timerID = setInterval(() => this.tick(), 1000);

我为什么不能说(显然它不起作用)

Why can't I just say (obviously it doesn't work)

this.timerID = setInterval(this.tick(), 1000);

推荐答案

setInterval的第一个参数的类型为function.如果您这样写:

The first argument for setInterval is of type function. If you write this:

this.timerID = setInterval(this.tick(), 1000);

...然后，您不传递函数，而是立即执行函数this.tick，然后将该函数调用返回的值作为参数传递.

…then you don't pass a function, instead you execute the function this.tick immediately and then pass the value returned by that function call as an argument.

您可以这样写:

this.timerID = setInterval(this.tick, 1000);

如果省略括号，则会传递对this.tick函数的引用，该函数然后在1000毫秒后由setInterval执行.

If you omit the parentheses, you pass a reference to your this.tick function, which is then executed by setInterval after 1000 milliseconds.

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