检查 JavaScript setTimeout 是否已触发 [英] Checking if a JavaScript setTimeout has fired

问题描述

我希望能够通过 JavaScript 分派大量工作在浏览器中完成，从而使浏览器始终保持响应.

I'd like to be able to dispatch a bunch of work via JavaScript to be done in the browser in such a way that the browser stays responsive throughout.

我尝试采用的方法是将工作分块，将每个块传递给一个函数，然后该函数通过 setTimeout(func, 0) 调用排队.

The approach I'm trying to take is to chunk up the work, passing each chunk to a function that is then queued with a setTimeout(func, 0) call.

我需要知道所有工作何时完成，因此我将返回的计时器 ID 存储在映射中 (id -> true|false).在我获得计时器 ID 后，此映射在下一个代码块中设置为 false，排队函数在完成时将映射设置为 true...当然，排队函数不知道它的计时器 ID.

I need to know when all the work is done, so I'm storing the returned timer ID in a map (id -> true|false). This mapping is set to false in the next block of code after I have the timer ID, and the queued function sets the mapping to true when it completes... except, of course, the queued function doesn't know its timer ID.

也许有更好/更简单的方法……或者一些关于如何根据需要操纵地图的建议?

Maybe there's a better/easier way... or some advice on how I can manipulate my map as I need to?

推荐答案

我会将工作排在一个数组中，使用一个超时来处理队列并在队列为空时调用回调.类似的东西:

I would queue the work in an array, use one timeout to process the queue and call a callback once the queue is empty. Something like:

var work = [...];

var run = function(work, callback) {
    setTimeout(function() {
        if(work.length > 0) {
            process(work.shift());
            setTimeout(arguments.callee, 25);
        }
        else {
            callback();
        }
    }, 25);
};

run(work, function() {
    alert('Work is done!');
});

由于浏览器中的 JavaScript 是单线程的，因此运行多个超时并没有真正的优势(至少我认为这是你正在做的).它甚至可能会降低浏览器的速度.

As JavaScript in browsers is single threaded there is no real advantage to run multiple timeouts (at least I think this is what you are doing). It may even slow down the browser.

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