Here’s the basic Javacript debounce function from Underscore.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);
	};
};

What’s happening?

Basically, you pass it a function and it will set a Timeout, to call .apply() on the function. This method runs the function with a given scope. In order to make sure that it doesn’t just build up a queue of function calls, it clears the existing timeout before it creates a new one. The function has the option to run the function immediately wihtout waiting for the timeout. I would think this is what you want to do everytime.