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