Timed chunk

timedChunk.js

/*! Copyright 2009 Nicholas C. Zakas. All rights reserved. MIT Licensed */
/**
 * Processes each item in "items" at most 50ms at a time with a sleep of 25ms.
 * By limiting the amount of time spent in a loop, there is no lock on the UI thread.
 *
 * Calls "process" in "context" for each item in "items".
 * After each item has been processed, "callback" is called with the original array.
 *
 * Some modifications to Zakas's code:
 * * added delay parameter to control how long to sleep
 * * added maxItems parameter to control the number of items looped at a time
 * * syntax tweaks and minor optimizations
 */
function timedChunk(items, process, context, callback, delay, maxItems) {
	var n = items.length,
		delay = delay || 25,
		maxItems = maxItems || n,
		i = 0;
	
	setTimeout(function chunkTimer(){
		var start = +new Date(),
			j = i;
		
		while (i < n && (i - j) < maxItems && (new Date() - start < 50)) {
			process.call(context, items[i]);
			i += 1;
		}
		
		if (i < n) {
			setTimeout(chunkTimer, delay);
		}
		else {
			callback(items);
		}
	}, 25);
}

Zakas's original code from: http://www.nczonline.net/blog/2009/08/11/timed-array-processing-in-javascript/

Would you be willing to explain how to use this for a more novice JS user? I'm confused about what the process, callback, and context, are doing? Could you show an example of how this works?

Thanks!