function addInputCallback(theInput,callback,delay){
	var timer=null;
	var theOldValue = '';
	theInput.onkeyup=function(event){
		if ( typeof event == "undefined" ) event = window.event;
		var key=event.keyCode;
		var keychar = String.fromCharCode(key);
		keychar = keychar.toLowerCase();
		if (key == 13) { // if enter key, call callback() function immediately
			timer=null;
			callback();
			theInput=null;
		}
		if (isAlphanumericInput(keychar) || key == 8 || key == 46) { // backspace and delete chars
			if(timer) {
				window.clearTimeout(timer);
			}
			timer=window.setTimeout(function(){
											 timer=null;
											 callback();
											 }
									,delay);
			theInput=null;
		}
	};
}

function isAlphanumericInput(theInputChar) {
	if ((("abcdefghijklmnopqrstuvwxyz0123456789").indexOf(theInputChar) > -1)) {
		return true;
	}
}