index.js

/*! (c) Andrea Giammarchi - ISC */
var self = this || {};
try { self.WeakMap = WeakMap; }
catch (WeakMap) {
  // this could be better but 90% of the time
  // it's everything developers need as fallback
  self.WeakMap = (function (id, Object) {'use strict';
    var dP = Object.defineProperty;
    var hOP = Object.hasOwnProperty;
    var proto = WeakMap.prototype;
    proto.delete = function (key) {
      return this.has(key) && delete key[this._];
    };
    proto.get = function (key) {
      return this.has(key) ? key[this._] : void 0;
    };
    proto.has = function (key) {
      return hOP.call(key, this._);
    };
    proto.set = function (key, value) {
      dP(key, this._, {configurable: true, value: value});
      return this;
    };
    return WeakMap;
    function WeakMap(iterable) {
      dP(this, '_', {value: '_@ungap/weakmap' + id++});
      if (iterable)
        iterable.forEach(add, this);
    }
    function add(pair) {
      this.set(pair[0], pair[1]);
    }
  }(Math.random(), Object));
}