'use strict'; var shared = require('../internals/shared'); var getBuiltIn = require('../internals/get-built-in'); var uncurryThis = require('../internals/function-uncurry-this'); var isSymbol = require('../internals/is-symbol'); var wellKnownSymbol = require('../internals/well-known-symbol'); var Symbol = getBuiltIn('Symbol'); var $isWellKnownSymbol = Symbol.isWellKnownSymbol; var getOwnPropertyNames = getBuiltIn('Object', 'getOwnPropertyNames'); var thisSymbolValue = uncurryThis(Symbol.prototype.valueOf); var WellKnownSymbolsStore = shared('wks'); for (var i = 0, symbolKeys = getOwnPropertyNames(Symbol), symbolKeysLength = symbolKeys.length; i < symbolKeysLength; i++) { // some old engines throws on access to some keys like `arguments` or `caller` try { var symbolKey = symbolKeys[i]; if (isSymbol(Symbol[symbolKey])) wellKnownSymbol(symbolKey); } catch (error) { /* empty */ } } // `Symbol.isWellKnownSymbol` method // https://tc39.es/proposal-symbol-predicates/#sec-symbol-iswellknownsymbol // We should patch it for newly added well-known symbols. If it's not required, this module just will not be injected module.exports = function isWellKnownSymbol(value) { if ($isWellKnownSymbol && $isWellKnownSymbol(value)) return true; try { var symbol = thisSymbolValue(value); for (var j = 0, keys = getOwnPropertyNames(WellKnownSymbolsStore), keysLength = keys.length; j < keysLength; j++) { // eslint-disable-next-line eqeqeq -- polyfilled symbols case if (WellKnownSymbolsStore[keys[j]] == symbol) return true; } } catch (error) { /* empty */ } return false; };