Question

I’m trying to figure out a way to emulate AS3’s Timer class.

If you’re not familiar, one of the cool things you can do is add duration to the timer even if it’s already running. This functionality has a lot of very nice uses.

Anyone have any thoughts on doing this in js?

Answer 1

I’m not familiar with this class, but you can easily create something similar in JavaScript:

function Timer(callback, time) {
    this.setTimeout(callback, time);
}

Timer.prototype.setTimeout = function(callback, time) {
    var self = this;
    if(this.timer) {
        clearTimeout(this.timer);
    }
    this.finished = false;
    this.callback = callback;
    this.time = time;
    this.timer = setTimeout(function() {
         self.finished = true;
        callback();
    }, time);
    this.start = Date.now();
}

Timer.prototype.add = function(time) {
   if(!this.finished) {
       // add time to time left
       time = this.time - (Date.now() - this.start) + time;
       this.setTimeout(this.callback, time);
   }
}

Usage:

var timer = new Timer(function() { // init timer with 5 seconds
    alert('foo');
}, 5000);

timer.add(2000); // add two seconds