找到setTimeout（）中剩下的时间？ [英] find the time left in a setTimeout()?
问题描述
我正在编写一些Javascript，它与我不拥有的库代码交互，并且不能（合理地）改变。它创建了Javascript超时，用于在一系列限时问题中显示下一个问题。这不是真正的代码，因为它超出了所有希望。这是图书馆正在做的事情：
I'm writing some Javascript that interacts with library code that I don't own, and can't (reasonably) change. It creates Javascript timeouts used for showing the next question in a series of time-limited questions. This isn't real code because it is obfuscated beyond all hope. Here's what the library is doing:
....
// setup a timeout to go to the next question based on user-supplied time
var t = questionTime * 1000
test.currentTimeout = setTimeout( showNextQuestion(questions[i+1]), t );
我想在屏幕上放置一个进度条，填充 questionTime * 1000 通过询问由 setTimeout 创建的计时器。唯一的问题是，似乎没有办法做到这一点。我缺少一个 getTimeout 函数吗？我能找到的关于Javascript超时的唯一信息仅与通过 setTimeout（函数，时间）创建，并通过 clearTimeout（id）。
I want to put a progress bar onscreen that fills towards questionTime * 1000 by interrogating the timer created by setTimeout. The only problem is, there seems to be no way to do this. Is there a getTimeout function that I'm missing? The only information on Javascript timeouts that I can find is related only to creation via setTimeout( function, time) and deletion via clearTimeout( id ).
我正在寻找一个函数，它返回超时触发前的剩余时间，或者调用超时后经过的时间。我的进度条形码如下所示：
I'm looking for a function that returns either the time remaining before a timeout fires, or the time elapsed after a timeout has been called. My progress bar code looks like this:
var timeleft = getTimeout( test.currentTimeout ); // I don't know how to do this
var $bar = $('.control .bar');
while ( timeleft > 1 ) {
$bar.width(timeleft / test.defaultQuestionTime * 1000);
}
tl; dr：如何在a之前找到剩余的时间javascript setTimeout（）？
这是我现在使用的解决方案。我经历了负责测试的图书馆部分，并解密了代码（可怕，并且违反了我的权限）。
Here's the solution I'm using now. I went through the library section that's in charge of tests, and unscrambled the code (terrible, and against my permissions).
// setup a timeout to go to the next question based on user-supplied time
var t = questionTime * 1000
test.currentTimeout = mySetTimeout( showNextQuestion(questions[i+1]), t );
这是我的代码：
// wrapper for setTimeout
function mySetTimeout( func, timeout ) {
timeouts[ n = setTimeout( func, timeout ) ] = {
start: new Date().getTime(),
end: new Date().getTime() + timeout
t: timeout
}
return n;
}这在任何不是IE 6的浏览器中都能很好地发挥作用。即使是最初的iPhone，我也希望能有所收获异步。
This works pretty spot-on in any browser that isn't IE 6. Even the original iPhone, where I expected things to get asynchronous.
推荐答案
如果您无法修改库代码，则需要重新定义setTimeout以满足您的需要。以下是您可以执行的操作的示例：
If you can't modify the library code, you'll need to redefine setTimeout to suit your purposes. Here's an example of what you could do:
(function () {
var nativeSetTimeout = window.setTimeout;
window.bindTimeout = function (listener, interval) {
function setTimeout(code, delay) {
var elapsed = 0,
h;
h = window.setInterval(function () {
elapsed += interval;
if (elapsed < delay) {
listener(delay - elapsed);
} else {
window.clearInterval(h);
}
}, interval);
return nativeSetTimeout(code, delay);
}
window.setTimeout = setTimeout;
setTimeout._native = nativeSetTimeout;
};
}());
window.bindTimeout(function (t) {console.log(t + "ms remaining");}, 100);
window.setTimeout(function () {console.log("All done.");}, 1000);
这不是生产代码，但应该让你走上正轨。请注意，每个超时只能绑定一个侦听器。我没有对此进行过广泛的测试，但它在Firebug中有效。
This is not production code, but it should put you on the right track. Note that you can only bind one listener per timeout. I haven't done extensive testing with this, but it works in Firebug.
更强大的解决方案将使用相同的包装setTimeout技术，而是使用来自返回的timeoutId给侦听器每个超时处理多个侦听器。您也可以考虑包装clearTimeout，以便在超时被清除时分离您的侦听器。
A more robust solution would use the same technique of wrapping setTimeout, but instead use a map from the returned timeoutId to listeners to handle multiple listeners per timeout. You might also consider wrapping clearTimeout so you can detach your listener if the timeout is cleared.
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