Symbol : Object

Symbols are an alternate to using %%/String|Strings%% as the

keys for properties. Symbols allow hiding properties on Objects

since you can only access the values if you have the same instance of the

Symbol.

You access a property with a Symbol key using

%%/Object#indexer_Symbol|object[symbol]%%.

Version:

ECMAScript 2015

Primitive:

true

Spec:

http://www.ecma-international.org/ecma-262/10.0/#sec-symbol-objects

----

Symbol([description : String]) : Symbol

Creates a new Symbol with an optional description.

<example>

var myObject = { foo: 'bar' };

var mySymbol = Symbol('MySymbol');

myObject[mySymbol] = 'baz';

console.log(myObject[mySymbol]);

// The property cannot be accessed using a string

console.log(myObject['MySymbol']);

</example>

Spec:

http://www.ecma-international.org/ecma-262/10.0/#sec-symbol-description

----

instance.description : String

Returns the description passed to the Symbol during construction.

<example>

var mySymbol = Symbol('MySymbol');

console.log(mySymbol.description);

</example>

Spec:

https://tc39.es/ecma262/#sec-symbol.prototype.description

Version:

ECMAScript 2019

----

asyncIterator : Symbol

Spec:

https://tc39.es/ecma262/#sec-symbol.asynciterator

----

hasInstance : Symbol

Spec:

http://www.ecma-international.org/ecma-262/10.0/#sec-symbol.hasinstance

----

isConcatSpreadable : Symbol

Spec:

http://www.ecma-international.org/ecma-262/10.0/#sec-symbol.isconcatspreadable

----

iterator : Symbol

The Symbol that retrieves a function that returns an

%%/Iterator|iterator%% for the Object.

<example>

// Array's iterator function is also exposed as 'values'

var arrayIterator = Array.prototype[Symbol.iterator];

console.log(arrayIterator === Array.prototype.values);

var x = ['a', 'b', 'c'];

// The following are all equivalent:

for (var item of x[Symbol.iterator]()) {

console.log(item);

}

// for (... of ...) automatically invokes the iterator function

for (var item of x) {

console.log(item);

}

// Array[Symbol.iterator] is also available through Array.values

for (var item of x.values()) {

console.log(item);

}

</example>

Spec:

http://www.ecma-international.org/ecma-262/10.0/#sec-symbol.iterator

----

match : Symbol

Spec:

http://www.ecma-international.org/ecma-262/10.0/#sec-symbol.match

----

matchAll : Symbol

Spec:

https://tc39.es/ecma262/#sec-symbol.matchall

----

replace : Symbol

Spec:

http://www.ecma-international.org/ecma-262/10.0/#sec-symbol.replace

----

search : Symbol

Spec:

http://www.ecma-international.org/ecma-262/10.0/#sec-symbol.search

----

species : Symbol

Spec:

http://www.ecma-international.org/ecma-262/10.0/#sec-symbol.species

----

split : Symbol

Spec:

http://www.ecma-international.org/ecma-262/10.0/#sec-symbol.split

----

toPrimitive : Symbol

Spec:

http://www.ecma-international.org/ecma-262/10.0/#sec-symbol.toprimitive

----

toStringTag : Symbol

Spec:

http://www.ecma-international.org/ecma-262/10.0/#sec-symbol.tostringtag

----

unscopables : Symbol

Spec:

http://www.ecma-international.org/ecma-262/10.0/#sec-symbol.unscopables

----

for(key : String) : Symbol

Spec:

http://www.ecma-international.org/ecma-262/10.0/#sec-symbol.for

----

keyFor(key : String) : Symbol

Spec:

http://www.ecma-international.org/ecma-262/10.0/#sec-symbol.for