Yang Guo | 4fd355c | 2019-09-19 08:59:03 | [diff] [blame] | 1 | 'use strict'; |
| 2 | |
| 3 | var keys = require('object-keys'); |
| 4 | |
| 5 | module.exports = function hasSymbols() { |
| 6 | if (typeof Symbol !== 'function' || typeof Object.getOwnPropertySymbols !== 'function') { return false; } |
| 7 | if (typeof Symbol.iterator === 'symbol') { return true; } |
| 8 | |
| 9 | var obj = {}; |
| 10 | var sym = Symbol('test'); |
| 11 | var symObj = Object(sym); |
| 12 | if (typeof sym === 'string') { return false; } |
| 13 | |
| 14 | if (Object.prototype.toString.call(sym) !== '[object Symbol]') { return false; } |
| 15 | if (Object.prototype.toString.call(symObj) !== '[object Symbol]') { return false; } |
| 16 | |
Tim van der Lippe | 16aca39 | 2020-11-13 11:37:13 | [diff] [blame] | 17 | /* |
| 18 | * temp disabled per https://github.com/ljharb/object.assign/issues/17 |
| 19 | * if (sym instanceof Symbol) { return false; } |
| 20 | * temp disabled per https://github.com/WebReflection/get-own-property-symbols/issues/4 |
| 21 | * if (!(symObj instanceof Symbol)) { return false; } |
| 22 | */ |
Yang Guo | 4fd355c | 2019-09-19 08:59:03 | [diff] [blame] | 23 | |
| 24 | var symVal = 42; |
| 25 | obj[sym] = symVal; |
Tim van der Lippe | 16aca39 | 2020-11-13 11:37:13 | [diff] [blame] | 26 | for (sym in obj) { return false; } // eslint-disable-line no-unreachable-loop |
Yang Guo | 4fd355c | 2019-09-19 08:59:03 | [diff] [blame] | 27 | if (keys(obj).length !== 0) { return false; } |
| 28 | if (typeof Object.keys === 'function' && Object.keys(obj).length !== 0) { return false; } |
| 29 | |
| 30 | if (typeof Object.getOwnPropertyNames === 'function' && Object.getOwnPropertyNames(obj).length !== 0) { return false; } |
| 31 | |
| 32 | var syms = Object.getOwnPropertySymbols(obj); |
| 33 | if (syms.length !== 1 || syms[0] !== sym) { return false; } |
| 34 | |
| 35 | if (!Object.prototype.propertyIsEnumerable.call(obj, sym)) { return false; } |
| 36 | |
| 37 | if (typeof Object.getOwnPropertyDescriptor === 'function') { |
| 38 | var descriptor = Object.getOwnPropertyDescriptor(obj, sym); |
| 39 | if (descriptor.value !== symVal || descriptor.enumerable !== true) { return false; } |
| 40 | } |
| 41 | |
| 42 | return true; |
| 43 | }; |