javascript - find the time left in a setTimeout()?

Question

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 );

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 ).

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: How do I find the time remaining before a javascript setTimeout()?

---

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 );

and here's my code:

// 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;
}

This works pretty spot-on in any browser that isn't IE 6. Even the original iPhone, where I expected things to get asynchronous.

Answer 1

Just for the record, there is a way to get the time left in node.js:

var timeout = setTimeout(function() {}, 3600 * 1000);

setInterval(function() {
    console.log('Time left: '+getTimeLeft(timeout)+'s');
}, 2000);

function getTimeLeft(timeout) {
    return Math.ceil((timeout._idleStart + timeout._idleTimeout - Date.now()) / 1000);
}

Prints:

$ node test.js 
Time left: 3599s
Time left: 3597s
Time left: 3595s
Time left: 3593s

This doesn't seem to work in firefox through, but since node.js is javascript, I thought this remark might be helpful for people looking for the node solution.