WeakMap polyfill

WeakMap.js

;(function(root) {
  function WeakMap() {
    if (!(this instanceof WeakMap)) {
      throw new TypeError('Illegal invocation')
    }
    var indexes = []
      , values = []
    this.has = _has.bind(this, indexes, values)
    this.set = _set.bind(this, indexes, values)
    this.get = _get.bind(this, indexes, values)
    this['delete'] = _delete.bind(this, indexes, values)
    this.clear = _clear.bind(this, indexes, values)
  }
 
  function _has(indexes, values, key) {
    return indexes.indexOf(key) > -1
  }
 
  function _set(indexes, values, key, value) {
    var index
    if (this.has(key)) {
      index = indexes.indexOf(key)
    } else {
      index = indexes.length
      indexes.push(key);
    }
    values[index] = value
  }
 
  function _get(indexes, values, key, defaultValue) {
    return this.has(key) ? values[indexes.indexOf(key)] : defaultValue
  }
 
  function _delete(indexes, values, key) {
    if (this.has(key)) {
      var index = indexes.indexOf(key)
      indexes.splice(index, 1)
      values.splice(index, 1)
    }
  }
 
  function _clear(indexes, values) {
    indexes.length = 0
    values.length = 0
  }
 
  root.WeakMap = WeakMap
}(this))

WeakMap.min.js

!function(a){function b(){if(!(this instanceof b))throw new TypeError("Illegal invocation");var a=[],h=[];this.has=c.bind(this,a,h),this.set=d.bind(this,a,h),this.get=e.bind(this,a,h),this["delete"]=f.bind(this,a,h),this.clear=g.bind(this,a,h)}function c(a,b,c){return a.indexOf(c)>-1}function d(a,b,c,d){var e;this.has(c)?e=a.indexOf(c):(e=a.length,a.push(c)),b[e]=d}function e(a,b,c,d){return this.has(c)?b[a.indexOf(c)]:d}function f(a,b,c){if(this.has(c)){var d=a.indexOf(c);a.splice(d,1),b.splice(d,1)}}function g(a,b){a.length=0,b.length=0}a.WeakMap=b}(this);