polyfill.js (2804B)
1 /** 2 * @license Apache-2.0 3 * 4 * Copyright (c) 2018 The Stdlib Authors. 5 * 6 * Licensed under the Apache License, Version 2.0 (the "License"); 7 * you may not use this file except in compliance with the License. 8 * You may obtain a copy of the License at 9 * 10 * http://www.apache.org/licenses/LICENSE-2.0 11 * 12 * Unless required by applicable law or agreed to in writing, software 13 * distributed under the License is distributed on an "AS IS" BASIS, 14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 15 * See the License for the specific language governing permissions and 16 * limitations under the License. 17 */ 18 19 'use strict'; 20 21 // MODULES // 22 23 var propertyNames = require( './../../property-names' ); 24 var propertySymbols = require( './../../property-symbols' ); 25 var propertyDescriptor = require( './../../property-descriptor' ); 26 var defineProperty = require( './../../define-property' ); 27 28 29 // MAIN // 30 31 /** 32 * Returns an object's own property descriptors. 33 * 34 * ## Notes 35 * 36 * - In contrast to the built-in `Object.getOwnPropertyDescriptors()`, this function returns an empty object if provided `undefined` or `null`, rather than throwing an error. 37 * 38 * @private 39 * @param {*} value - input object 40 * @returns {Object} property descriptors 41 * 42 * @example 43 * var obj = { 44 * 'beep': 'boop', 45 * 'foo': 3.14 46 * }; 47 * 48 * var desc = getOwnPropertyDescriptors( obj, 'foo' ); 49 * // returns {...} 50 */ 51 function getOwnPropertyDescriptors( value ) { 52 var symbols; 53 var names; 54 var desc; 55 var out; 56 var i; 57 58 out = {}; 59 60 // Get the value's own enumerable and non-enumerable properties: 61 names = propertyNames( value ); 62 63 // For each property name, retrieve the property descriptor... 64 for ( i = 0; i < names.length; i++ ) { 65 desc = propertyDescriptor( value, names[ i ] ); 66 if ( desc ) { 67 // The following is equivalent to `out[ names[i] ] = desc`, but accounts for the possibility of a "poisoned" `Object` prototype (i.e., an `Object.prototype` having a property with a setter which throws). 68 defineProperty( out, names[ i ], { 69 'configurable': true, 70 'enumerable': true, 71 'writable': true, 72 'value': desc 73 }); 74 } 75 } 76 77 // Get the value's symbol properties: 78 symbols = propertySymbols( value ); 79 80 // For each symbol property, retrieve the property descriptor... 81 for ( i = 0; i < symbols.length; i++ ) { 82 desc = propertyDescriptor( value, symbols[ i ] ); 83 if ( desc ) { 84 // The following is equivalent to `out[ symbols[i] ] = desc`, but accounts for the possibility of a "poisoned" `Object` prototype (i.e., an `Object.prototype` having a property with a setter which throws). 85 defineProperty( out, symbols[ i ], { 86 'configurable': true, 87 'enumerable': true, 88 'writable': true, 89 'value': desc 90 }); 91 } 92 } 93 94 return out; 95 } 96 97 98 // EXPORTS // 99 100 module.exports = getOwnPropertyDescriptors;