resources/src/polyfill-object-create.js

   1 /**
   2  * Simplified version of es5-sham#Object-create that also works around a bug
   3  * in the actual es5-sham: https://github.com/es-shims/es5-shim/issues/252
   4  *
   5  * Does not:
   6  * - Support empty inheritance via `Object.create(null)`.
   7  * - Support getter and setter accessors via `Object.create( .., properties )`.
   8  * - Support custom property descriptor (e.g. writable, configurtable, enumerable).
   9  * - Leave behind an enumerable "__proto__" all over the place.
  10  *
  11  * @author Timo Tijhof, 2014
  12  */
  13
  14 // ES5 15.2.3.5
  15 // http://es5.github.com/#x15.2.3.5
  16 if ( !Object.create ) {
  17         ( function () {
  18                 var hasOwn = Object.hasOwnProperty,
  19                         // https://developer.mozilla.org/en-US/docs/ECMAScript_DontEnum_attribute#JScript_DontEnum_Bug
  20                         // http://whattheheadsaid.com/2010/10/a-safer-object-keys-compatibility-implementation
  21                         isEnumBug = !{ valueOf: 0 }.propertyIsEnumerable( 'valueOf' );
  22
  23                 // Reusable constructor function for Object.create
  24                 function Empty() {}
  25
  26                 function defineProperty( object, key, property ) {
  27                         if ( hasOwn.call( property, 'value' ) ) {
  28                                 object[ key ] = property.value;
  29                         } else {
  30                                 object[ key ] = property;
  31                         }
  32                 }
  33
  34                 Object.create = function create( prototype, properties ) {
  35                         var object, key;
  36
  37                         if ( prototype !== Object( prototype ) ) {
  38                                 throw new TypeError( 'Called on non-object' );
  39                         }
  40
  41                         Empty.prototype = prototype;
  42                         object = new Empty();
  43
  44                         if ( properties !== undefined ) {
  45                                 if ( !isEnumBug ) {
  46                                         for ( key in properties ) {
  47                                                 if ( hasOwn.call( properties, key ) ) {
  48                                                         defineProperty( object, key, properties[ key ] );
  49                                                 }
  50                                         }
  51                                 } else {
  52                                         Object.keys( properties ).forEach( function ( key ) {
  53                                                 defineProperty( object, key, properties[ key ] );
  54                                         } );
  55                                 }
  56                         }
  57
  58                         return object;
  59                 };
  60
  61         }() );
  62 }