well-known-symbol.js 1.04 KB
var global = require('../internals/global');
var shared = require('../internals/shared');
var hasOwn = require('../internals/has-own-property');
var uid = require('../internals/uid');
var NATIVE_SYMBOL = require('../internals/symbol-constructor-detection');
var USE_SYMBOL_AS_UID = require('../internals/use-symbol-as-uid');

var WellKnownSymbolsStore = shared('wks');
var Symbol = global.Symbol;
var symbolFor = Symbol && Symbol['for'];
var createWellKnownSymbol = USE_SYMBOL_AS_UID ? Symbol : Symbol && Symbol.withoutSetter || uid;

module.exports = function (name) {
  if (!hasOwn(WellKnownSymbolsStore, name) || !(NATIVE_SYMBOL || typeof WellKnownSymbolsStore[name] == 'string')) {
    var description = 'Symbol.' + name;
    if (NATIVE_SYMBOL && hasOwn(Symbol, name)) {
      WellKnownSymbolsStore[name] = Symbol[name];
    } else if (USE_SYMBOL_AS_UID && symbolFor) {
      WellKnownSymbolsStore[name] = symbolFor(description);
    } else {
      WellKnownSymbolsStore[name] = createWellKnownSymbol(description);
    }
  } return WellKnownSymbolsStore[name];
};