lodash/test/asset/weakmap.js

;(function() {

  /** Used to determine if values are of the language type Object */
  var objectTypes = {
    'function': true,
    'object': true
  };

  /** Used as the `WeakMap#toString` return value */
  var nativeString = String(Object.prototype.toString).replace(/toString/g, 'WeakMap');

  /** Used as a reference to the global object */
  var root = (objectTypes[typeof window] && window) || this;

  /** Detect free variable `global` from Node.js or Browserified code and use it as `root` */
  var freeGlobal = objectTypes[typeof global] && global;
  if (freeGlobal && (freeGlobal.global === freeGlobal || freeGlobal.window === freeGlobal || freeGlobal.self === freeGlobal)) {
    root = freeGlobal;
  }

  /*--------------------------------------------------------------------------*/

  /**
   * Creates a `WeakMap` object.
   */
  function WeakMap() {
    // no-op
  }

  /*--------------------------------------------------------------------------*/

  /**
   * Gets the value associated with the given key.
   *
   * @memberOf WeakMap
   * @param {Object} key The key object.
   * @returns {*} Returns the associated value, else `undefined`.
   */
  function get(key) {
    return key.__weakmap__;
  }

  /**
   * Sets a value for the given key.
   *
   * @memberOf WeakMap
   * @param {Object} key The key object.
   * @param {*} value The value to set.
   */
  function set(key, value) {
    key.__weakmap__ = value;
    return this;
  }

  /**
   * Produces the `toString` result of `WeakMap`.
   *
   * @static
   * @memberOf WeakMap
   * @returns {string} Returns the string result.
   */
  function toString() {
    return nativeString;
  }

  /*--------------------------------------------------------------------------*/

  WeakMap.toString = toString;
  WeakMap.prototype.get = get;
  WeakMap.prototype.set = set;

  // expose `WeakMap`
  if (!root.WeakMap) {
    root.WeakMap = WeakMap;
  }
}.call(this));