atom-nuclide/pkg/commons-node/once.js

A unified developer experience for web and mobile development, built as a suite of features on top of Atom to provide hackability and the support of an active community.

Object.defineProperty(exports, '__esModule', {
  value: true
});
exports.default = once;

/*
 * Copyright (c) 2015-present, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the license found in the LICENSE file in
 * the root directory of this source tree.
 */

function once(fn) {
  var fnMaybe = fn;
  var ret = undefined;
  return function () {
    // The type gymnastics here are so `fn` can be
    // garbage collected once we've used it.
    if (!fnMaybe) {
      return ret;
    } else {
      ret = fnMaybe.apply(this, arguments);
      fnMaybe = null;
      return ret;
    }
  };
}

module.exports = exports.default;