scroll-throttle.js

function throttle( func, limit ){
    var inThrottle;
	var lastFunc;
	var lastRan;

	return function() {
		var context = this;
		var args = arguments;
		if (!inThrottle) {
			func.apply(context, args);
			lastRan = Date.now();
			inThrottle = true;
		} else {
			clearTimeout(lastFunc);
			lastFunc = setTimeout(function() {
				if ((Date.now() - lastRan) >= limit) {
					func.apply(context, args);
					lastRan = Date.now();
				}
			}, limit - (Date.now() - lastRan));
		}
	}
}