Bind a keyup event with a delay, as seen here: http://stackoverflow.com/questions/1909441/jquery-keyup-delay

jquery.delayedkeyup.js

(function( $ ){
  $.fn.delayedKeyup = function(period, handler) {

      var delayedHandler = (function() {
          var timer = 0;
          return function(callback, miliSeconds) {
              clearTimeout(timer);
              timer = setTimeout(callback, miliSeconds);
          }
      })();

      this.bind('keyup', function(event) {
          delayedHandler(handler(event), 300);
      });

  };
})( jQuery );