41 lines
1.0 KiB
JavaScript
41 lines
1.0 KiB
JavaScript
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'use strict';
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var callBound = require('call-bound');
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var $toString = callBound('Object.prototype.toString');
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var hasSymbols = require('has-symbols')();
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var safeRegexTest = require('safe-regex-test');
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if (hasSymbols) {
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var $symToStr = callBound('Symbol.prototype.toString');
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var isSymString = safeRegexTest(/^Symbol\(.*\)$/);
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/** @type {(value: object) => value is Symbol} */
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var isSymbolObject = function isRealSymbolObject(value) {
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if (typeof value.valueOf() !== 'symbol') {
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return false;
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}
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return isSymString($symToStr(value));
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};
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/** @type {import('.')} */
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module.exports = function isSymbol(value) {
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if (typeof value === 'symbol') {
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return true;
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}
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if (!value || typeof value !== 'object' || $toString(value) !== '[object Symbol]') {
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return false;
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}
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try {
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return isSymbolObject(value);
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} catch (e) {
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return false;
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}
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};
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} else {
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/** @type {import('.')} */
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module.exports = function isSymbol(value) {
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// this environment does not support Symbols.
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return false && value;
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};
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}
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