basic function throttling utility function

throttlefn.js

  // returns a throttled function that never runs more than every `delay` milliseconds
  // the returned function also has a nice .finish() method.
  $.throttleFn = function (func, skipFirst, delay) {
      if ( typeof skipFirst === 'number' )
      {
        delay = skipFirst;
        skipFirst = false;
      }
      delay = delay || 50;
      var throttled = 0,
          timeout,
          _args,
          _this,
          throttledFn = function () {
              _args = arguments;
              _this = this;
              if ( !throttled )
              {
                skipFirst ?
                    throttled++:
                    func.apply(_this, _args);
                timeout = setTimeout(throttledFn.finish, delay);
              }
              throttled++;
            };
      throttledFn.finish = function () {
          timeout && clearTimeout( timeout );
          throttled>1 && func.apply(_this, _args);
          throttled = 0;
        };
      return throttledFn;
    };