throttle.js

      var throttle = function(fn, delay) {
           delay || (delay = 100);
           var throttle = false;
           return function(){
               if (throttle){ return; } // you no enter
               throttle = setTimeout(function(){ 
                 // tail it - and do one last ajax request
                 fn.apply(this, arguments);
                 throttle = false; 
                 }, delay);
               fn.apply(this, arguments);
           };
       };
      
      field.on("keyup", throttle(keyUpFn.bind(this), 2000));

This is beautiful simplicity I needed. Thanks for capturing this solution.