Constructor that create a Loop object to run blocking loops, but allow it to be interrupted when requested to give a change to make DOM updates.

AsyncLoop.js

/** Constructor that create a Loop object to run blocking loops, but allow
 * it to be interrupted when requested to give a change to make DOM updates
 * @author Victor B - www.vitim.us
*/
function AsyncLoop(){
	this.loop; //called on every loop
	this.onUpdate; //called when the loop is interrupted
	this.onComplete; //called when the loop is finished
    
    this.requestInterruptToUpdateDOM = false;
}
AsyncLoop.prototype.run = function(){
	var self = this;
	function loop(){
		while(true){
			//do stuff
			if(!self.loop.call()){
				if(self.onComplete) self.onComplete();
				return;
			}
            if(self.requestInterruptToUpdateDOM) break; //break loop to let DOM update
		}
		if(self.onUpdate) self.onUpdate();
		setTimeout(loop, 0); //async resume loop;
	}
	loop();
}

/* example

	var A = new AsyncLoop();
	
    A.loop = function(){
        
        //do some extensive computation
        
        //show progress every n iterarions
        if() A.requestInterruptToUpdateDOM = true;
        
        //when done return false to break the look
        return !done;
    }
    A.onUpdate = function(){
    	//print progress
    }
    A.onComplete = function(){
        //done
        //print results
    }
    
    A.run();
*/