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