Function throttle

Sortable.js:477–492

(callback, ms)

  }
  var _throttleTimeout;
  function throttle(callback, ms) {
    return function () {
      if (!_throttleTimeout) {
        var args = arguments,
          _this = this;
        if (args.length === 1) {
          callback.call(_this, args[0]);
        } else {
          callback.apply(_this, args);
        }
        _throttleTimeout = setTimeout(function () {
          _throttleTimeout = void 0;
        }, ms);
      }
    };
  }
  function cancelThrottle() {
    clearTimeout(_throttleTimeout);
    _throttleTimeout = void 0;