如何通过Javascript中的setTimeout终止无尽的while循环 [英] How to terminate endless while loop via setTimeout in Javascript

问题描述

我有一段带有while循环的代码，我想通过setTimeout()停止.但这似乎是一个永无止境的循环，永远不会触发setTimeout().如果我删除while循环，超时将正确触发.请问出什么事了?

I have a piece of code with while loop which I would like to stop by setTimeout(). But it seems like a endless loop, which never triggers setTimeout(). If I remove while loop, timeout triggers correctly. What is wrong please?

$(document).ready(function() 
{
    var i = 0, s = false;

    setTimeout( function()
    {
        s = true;
        console.log( "Timeuot!!!" );
        console.log( "s value is " + s );
    }, 1000 );

    while( s === false )
    {
        console.log( "this is while and s is " + s );
        i++;
    }

    console.log( "iterations: " + i );
});

推荐答案

JavaScript运行单个事件循环.它不会停止在函数中间，以查看是否有任何事件(例如单击或超时)会触发另一个函数.

JavaScript runs a single event loop. It won't stop in the middle of a function to see if there are any events (such as clicks or timeouts) that would trigger a different function.

简而言之:在while循环完成之前，它不会运行定时功能.

In short: It won't run the timed function until the while loop has finished.

要做这种事情，通常需要一个事件驱动的迭代器.

To do this sort of thing, you'd normally have an event driven iterator.

var i = 0,
  s = false;

setTimeout(function() {
  s = true;
  console.log("Timeuot!!!");
  console.log("s value is " + s);
}, 1000);

next();

function next() {
  if (s) {
    return done();
  }
  console.log({
    s, i
  });
  i++;
  setTimeout(next, 0);
}

function done() {
  console.log("iterations: " + i);
}

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