throttle.js

// begin http://sampsonblog.com/749/simple-throttle-function
  var throttle = function(callback, limit) {
      var wait = false;                     // Initially, we're not waiting
      return function () {                  // We return a throttled function
          if (!wait) {                      // If we're not waiting
              callback.call();              // Execute users function
              wait = true;                  // Prevent future invocations
              win.setTimeout(function () {  // After a period of time
                  wait = false;             // And allow future invocations
              }, limit);
          }
      }
  }
  // end