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