debian-mirror-gitlab/core-js/modules/es.symbol.description.js
2019-09-25 13:30:05 +05:30

50 lines
2.1 KiB
JavaScript

// `Symbol.prototype.description` getter
// https://tc39.github.io/ecma262/#sec-symbol.prototype.description
'use strict';
var $ = require('../internals/export');
var DESCRIPTORS = require('../internals/descriptors');
var global = require('../internals/global');
var has = require('../internals/has');
var isObject = require('../internals/is-object');
var defineProperty = require('../internals/object-define-property').f;
var copyConstructorProperties = require('../internals/copy-constructor-properties');
var NativeSymbol = global.Symbol;
if (DESCRIPTORS && typeof NativeSymbol == 'function' && (!('description' in NativeSymbol.prototype) ||
// Safari 12 bug
NativeSymbol().description !== undefined
)) {
var EmptyStringDescriptionStore = {};
// wrap Symbol constructor for correct work with undefined description
var SymbolWrapper = function Symbol() {
var description = arguments.length < 1 || arguments[0] === undefined ? undefined : String(arguments[0]);
var result = this instanceof SymbolWrapper
? new NativeSymbol(description)
// in Edge 13, String(Symbol(undefined)) === 'Symbol(undefined)'
: description === undefined ? NativeSymbol() : NativeSymbol(description);
if (description === '') EmptyStringDescriptionStore[result] = true;
return result;
};
copyConstructorProperties(SymbolWrapper, NativeSymbol);
var symbolPrototype = SymbolWrapper.prototype = NativeSymbol.prototype;
symbolPrototype.constructor = SymbolWrapper;
var symbolToString = symbolPrototype.toString;
var native = String(NativeSymbol('test')) == 'Symbol(test)';
var regexp = /^Symbol\((.*)\)[^)]+$/;
defineProperty(symbolPrototype, 'description', {
configurable: true,
get: function description() {
var symbol = isObject(this) ? this.valueOf() : this;
var string = symbolToString.call(symbol);
if (has(EmptyStringDescriptionStore, symbol)) return '';
var desc = native ? string.slice(7, -1) : string.replace(regexp, '$1');
return desc === '' ? undefined : desc;
}
});
$({ global: true, forced: true }, {
Symbol: SymbolWrapper
});
}