function to return a debouced js function which honours the orginal call context

debouce.js

	// Returns a function, that, as long as it continues to be invoked, will not
	// be triggered. The function will be called after it stops being called for
	// N milliseconds. If `immediate` is passed, trigger the function on the
	// leading edge, instead of the trailing.
	function debounce(func, wait, immediate) {
		var timeout;
		return function() {
			var context = this, args = arguments;
			var later = function() {
				timeout = null;
				if (!immediate) func.apply(context, args);
			};
			var callNow = immediate && !timeout;
			clearTimeout(timeout);
			timeout = setTimeout(later, wait);
			if (callNow) func.apply(context, args);
		};
	}