关键字'this'可以用来引用javascript中定时器内部的setInterval方法吗

Question

我已经知道setIntervaljavascript中的函数每隔固定的时间重复执行一个函数或一段代码。我已经知道它的语法如下：

setInterval(func|code, [delay], [arg1], [arg2], ...)

我的问题是：我可以使用关键字“this”作为参数来引用计时器 ID（我的例子中的所有参数都作为外部回调函数的参数传递）？

提前致谢。

Answer 1

在创建计时器之前，您不能直接传递计时器的 ID。问题是你必须调用&nbsp;setInterval才能获取 ID，然后才能将其实际传递给被调用的函数：let&nbsp;timerId&nbsp;=&nbsp;setInterval(function()&nbsp;{},&nbsp;1000,&nbsp;timerId);&nbsp; //error&nbsp;-&nbsp;we&nbsp;are&nbsp;using&nbsp;`timerId`&nbsp;before&nbsp;its&nbsp;declaration&nbsp;is&nbsp;finished传递一个对象但是，您可以利用对象在共享相同引用的情况下工作的方式。因此，您可以初始化一个对象，这意味着该变量存在，然后调用setInterval并将计时器ID记录为该对象的属性。然后将该对象作为参数传递给回调。当回调执行时，对象属性肯定会被填充，您可以只使用其中的值：let cb;{ //callback in one scope&nbsp;&nbsp;&nbsp; //simple counter that stops at zero&nbsp; let i = 3;&nbsp; cb = timerContext => {&nbsp; &nbsp; console.log(i--);&nbsp; &nbsp; if (i < 0) {&nbsp; &nbsp; &nbsp; console.log("finish");&nbsp; &nbsp; &nbsp; clearInterval(timerContext.timerId);&nbsp; &nbsp; }&nbsp; }}{//start the timer in a different scope&nbsp; let context = { timerId: null };&nbsp;&nbsp;&nbsp; context.timerId = setInterval(cb, 1000, context);}创建一个包装器或者，如果您在调用 setInterval 时为其创建包装函数，则只能向外部回调传递计时器 ID：let cb;{ //callback in one scope&nbsp;&nbsp;&nbsp; //simple counter that stops at zero&nbsp; let i = 3;&nbsp; cb = timerId => {&nbsp; &nbsp; console.log(i--);&nbsp; &nbsp; if (i < 0) {&nbsp; &nbsp; &nbsp; console.log("finish");&nbsp; &nbsp; &nbsp; clearInterval(timerId);&nbsp; &nbsp; }&nbsp; }}{//start the timer in a different scope&nbsp; let timerId = setInterval(() => cb(timerId), 1000);}传递为thisthis如果您愿意，如果您的回调是普通函数，则可以以任一方式将计时器 ID 作为上下文传递：目的let cb;{ //callback in one scope&nbsp;&nbsp;&nbsp; //simple counter that stops at zero&nbsp; let i = 3;&nbsp; cb = function() {&nbsp; &nbsp; console.log(i--);&nbsp; &nbsp; if (i < 0) {&nbsp; &nbsp; &nbsp; console.log("finish");&nbsp; &nbsp; &nbsp; clearInterval(this.timerId);&nbsp; &nbsp; }&nbsp; }}{//start the timer in a different scope&nbsp; let context = { timerId: null };&nbsp;&nbsp;&nbsp; context.timerId = setInterval(cb.bind(context), 1000);}只要身份证号let cb;{ //callback in one scope&nbsp;&nbsp;&nbsp; //simple counter that stops at zero&nbsp; let i = 3;&nbsp; cb = function() {&nbsp; &nbsp; console.log(i--);&nbsp; &nbsp; if (i < 0) {&nbsp; &nbsp; &nbsp; console.log("finish");&nbsp; &nbsp; &nbsp; clearInterval(this);&nbsp; &nbsp; }&nbsp; }}{//start the timer in a different scope&nbsp; let timerId = setInterval(() => cb.call(timerId), 1000);}