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   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  }