throttle.js

/**
 * Source: https://remysharp.com/2010/07/21/throttling-function-calls 
 */

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 = +new Date;
				fn.apply(context, args);
			}, threshhold + ( last - now ));
		} else {
			last = now;
			fn.apply(context, args);
		}
	};
}