JavaScript Debounce Function

debounce.js

//usage: http://jsbin.com/ucucuc
var debounce = function(delay,callback){
  var timeout;
  
  //$().keyup(debounce()) will be this function, it still has access to timeout because of closure
  return function(){
    var that = this,args = arguments,
    delayed = function(){
        callback.apply(that, args);
        timeout = null; 
    };
    //if we have already have something queued then clear it
    timeout && clearTimeout(timeout);
    //each time this is called set the timeout to something else
    timeout = setTimeout(delayed, delay || 250); 
    
  };
  
};