javascript: pause setTimeout();

You could wrap window.setTimeout like this, which I think is similar to what you were suggesting in the question:

var Timer = function(callback, delay) {    var timerId, start, remaining = delay;    this.pause = function() {        window.clearTimeout(timerId);        remaining -= Date.now() - start;    };    this.resume = function() {        start = Date.now();        window.clearTimeout(timerId);        timerId = window.setTimeout(callback, remaining);    };    this.resume();};var timer = new Timer(function() {    alert("Done!");}, 1000);timer.pause();// Do some stuff...timer.resume();

Something like this should do the trick.

function Timer(fn, countdown) {    var ident, complete = false;    function _time_diff(date1, date2) {        return date2 ? date2 - date1 : new Date().getTime() - date1;    }    function cancel() {        clearTimeout(ident);    }    function pause() {        clearTimeout(ident);        total_time_run = _time_diff(start_time);        complete = total_time_run >= countdown;    }    function resume() {        ident = complete ? -1 : setTimeout(fn, countdown - total_time_run);    }    var start_time = new Date().getTime();    ident = setTimeout(fn, countdown);    return { cancel: cancel, pause: pause, resume: resume };}

No. You'll need cancel it (clearTimeout), measure the time since you started it and restart it with the new time.