Better timers with closures and throttling through debouncing methods. By Remy Sharp: http://remysharp.com/2010/07/21/throttling-function-calls/

timer.js

// Debounce without jQuery
function debounce(fn, delay) {
	var timer = null;
	return function () {
		var context = this, args = arguments;
		clearTimeout(timer);
		timer = setTimeout(function () {
			fn.apply(context, args);
		}, delay);
	};
}

// Use Debounce Fn with jQuery
$('input.username').keypress(debounce(function (event) {
	// do the Ajax request
}, 250));

// Throttling Function
function throttle(fn, threshhold, scope) {
	threshhold || (threshhold = 250);
	var last,
	deferTimer;

	return function () {
		var context = scope || this;
		
		var now = +new Date,
		args = arguments;
		if (last && now < last + threshhold) {
			// hold on to it
			clearTimeout(deferTimer);
			deferTimer = setTimeout(function () {
				last = now;
				fn.apply(context, args);
			}, threshhold);
		} else {
			last = now;
			fn.apply(context, args);
		}
	};
}

// Use throttle Fn with jQuery

$('body').on('mousemove', throttle(function (event) {
	console.log('tick');
}, 1000));