aaac7fed
 liuqimichale
add
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'use strict';
/* eslint complexity: [2, 17], max-statements: [2, 33] */
module.exports = function hasSymbols() {
if (typeof Symbol !== 'function' || typeof Object.getOwnPropertySymbols !== 'function') { return false; }
if (typeof Symbol.iterator === 'symbol') { return true; }
var obj = {};
var sym = Symbol('test');
var symObj = Object(sym);
if (typeof sym === 'string') { return false; }
if (Object.prototype.toString.call(sym) !== '[object Symbol]') { return false; }
if (Object.prototype.toString.call(symObj) !== '[object Symbol]') { return false; }
// temp disabled per https://github.com/ljharb/object.assign/issues/17
// if (sym instanceof Symbol) { return false; }
// temp disabled per https://github.com/WebReflection/get-own-property-symbols/issues/4
// if (!(symObj instanceof Symbol)) { return false; }
// if (typeof Symbol.prototype.toString !== 'function') { return false; }
// if (String(sym) !== Symbol.prototype.toString.call(sym)) { return false; }
var symVal = 42;
obj[sym] = symVal;
for (sym in obj) { return false; } // eslint-disable-line no-restricted-syntax
if (typeof Object.keys === 'function' && Object.keys(obj).length !== 0) { return false; }
if (typeof Object.getOwnPropertyNames === 'function' && Object.getOwnPropertyNames(obj).length !== 0) { return false; }
var syms = Object.getOwnPropertySymbols(obj);
if (syms.length !== 1 || syms[0] !== sym) { return false; }
if (!Object.prototype.propertyIsEnumerable.call(obj, sym)) { return false; }
if (typeof Object.getOwnPropertyDescriptor === 'function') {
var descriptor = Object.getOwnPropertyDescriptor(obj, sym);
if (descriptor.value !== symVal || descriptor.enumerable !== true) { return false; }
}
return true;
};
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