43 lines
1.7 KiB
JavaScript
43 lines
1.7 KiB
JavaScript
'use strict';
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/* eslint complexity: [2, 18], max-statements: [2, 33] */
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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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// 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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// if (typeof Symbol.prototype.toString !== 'function') { return false; }
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// if (String(sym) !== Symbol.prototype.toString.call(sym)) { return false; }
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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-restricted-syntax, no-unreachable-loop
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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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