js setTimeout synchronize

Question

In fact, when I use

setTimeout(a(),60);
setTimeout(a(),120);
setTimeout(a(),180);
setTimeout(a(),240);

It is supposed to be 60ms gap between calling's of a functions.

But it isnt, especially when it is fired during page loading or animating elements. In fact that gap gets even 2x longer when browser 'has hard work to do'. In some cases it can be visible easly.

The point of question is - is there any other way to synchronize events or functions in time in javascript?

you could wrap those calls into another function with a timeout of 60 seconds and call the 120 every second call, the 180 on every third time ... — m02ph3u5
– m02ph3u5, Commented Dec 31, 2012 at 1:06

Jasdeep Khalsa · Accepted Answer · 2012-12-31 01:14:43Z

3

The timing in setTimeout(a(),60) in simple terms translates to I will run this function no earlier than 60ms, but if I get busy it could be later than that.

Therefore, setTimeout does not promise when the execution will take place, only that it will take place sometime after the given time in milliseconds.

So to answer your question, no there is no way to guarantee execution time with setTimeout but you can load your script after the DOM has loaded so that JavaScript is not busy anymore loading other things. In jQuery you can use the $(document).ready() function for that purpose.

Read this article by John Resig for more information about timing in JavaScript: http://ejohn.org/blog/how-javascript-timers-work/

answered Dec 31, 2012 at 1:14

Jasdeep Khalsa

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Rudie · Accepted Answer · 2012-12-31 01:25:16Z

3

Try this:

setTimeout(a,60);
setTimeout(a,120);
setTimeout(a,180);
setTimeout(a,240);

Note that the function doesn't have the ()s.

edited Dec 31, 2012 at 1:25

Rudie

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answered Dec 31, 2012 at 1:04

Rui Jarimba

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PleaseStand · Accepted Answer · 2012-12-31 01:23:25Z

2

In your particular case, setInterval() might work:

var count = 0, interval = setInterval(function() {
    count += 1;
    if (count > 4) {
        clearInterval(interval);
    } else {
        a();
    }
}, 60);

Note that jQuery has a built-in animation feature that uses the different, better approach of simply treating an animation as a function of time and frequently checking the clock, so an unexpected delay would simply make the animation a bit less smooth.

answered Dec 31, 2012 at 1:23

PleaseStand

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1 Comment

Rudie Over a year ago

Or requestAnimationFrame but that takes getting used to.

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