Set : Object

Sets are a collection of %%/Object|Objects%% where each

object can only appear once in the set.

Iterable:

true

Version:

ECMAScript 2015

Spec:

http://www.ecma-international.org/ecma-262/6.0/#sec-set-objects

----

new Set() : Set

Creates an empty Set.

<example>

var x = new Set();

x.add(1);

x.add('a');

x.add({ foo: 'bar' });

for (var item of x) {

console.dir(item);

}

</example>

Spec:

http://www.ecma-international.org/ecma-262/6.0/#sec-set-iterable

----

new Set(iterable : Object) : Set

Creates a Set by iterating over **iterable** and adding

each value to the Set.

<example>

var fromArray = new Set([1, '1', { foo: 'bar' }]);

for (var item of fromArray) {

console.dir(item);

}

var generator = function*() {

yield 3;

yield 'javascript';

};

var fromGenerator = new Set(generator());

for (var item of fromGenerator) {

console.dir(item);

}

</example>

Spec:

http://www.ecma-international.org/ecma-262/6.0/#sec-set-iterable

----

instance.size : Number

The number of value in **this**.

<example>

var x = new Set(['a', 'b', 'c']);

console.log(x.size);

x.add('d');

console.log(x.size);

x.clear();

console.log(x.size);

</example>

Spec:

http://www.ecma-international.org/ecma-262/6.0/#sec-get-set.prototype.size

----

prototype.add(value : Object) : Set

Stores **value** in **this**. If **value** is already stored,

there is no change to the Set.

Returns **this**.

<example>

var x = new Set(['a', 'b', 'c']);

console.log(x.has('a'));

console.log(x.has('d'));

x.add('d');

console.log(x.has('d'));

</example>

Spec:

http://www.ecma-international.org/ecma-262/6.0/#sec-set.prototype.add

----

prototype.clear() : undefined

Clears all values from **this**.

<example>

var x = new Set(['a', 'b', 'c']);

console.log(x.size);

x.clear();

console.log(x.size);

</example>

Spec:

http://www.ecma-international.org/ecma-262/6.0/#sec-set.prototype.clear

----

prototype.delete(value : Object) : Boolean

Removes **value* from **this**.

Returns **true** if **value** was in **this** before deleting it.

<example>

var x = new Set(['a', 'b', 'c']);

console.log('size before delete: ' + x.size);

console.log('deleted "a" = ' + x.delete('a'));

console.log('size after delete: ' + x.size);

console.log('deleted "foo" = ' + x.delete('foo'));

</example>

Spec:

http://www.ecma-international.org/ecma-262/6.0/#sec-set.prototype.delete

----

prototype.entries() : Iterator

Returns an iterator of the items in **this** where the

%%Iterator#next|**values**s%% of the iterator are of the form

**[value : %%/Object|Object%%, value : %%/Object|Object%%]**

(**value** is duplicated twice).

See also %%#keys|**keys()**%% and %%#values|**values()**%%.

<example>

var x = new Set(['a', 'b', 'c']);

// Use for (... of ...) to loop over the iterator

for (var entry of x.entries()) {

console.dir(entry);

}

// Or access the iterator manually

var entries = x.entries();

console.dir(entries.next());

console.dir(entries.next());

console.dir(entries.next());

console.dir(entries.next());

</example>

Spec:

http://www.ecma-international.org/ecma-262/6.0/#sec-set.prototype.entries

----

prototype.forEach(callback(value : Object, key : Object, set : Set) : undefined, [thisArg : Object]) : undefined

Calls **callback** for each value in **this**.

The **Set** passed to **callback** is the **this** of the call to **forEach**.

<example>

var x = new Set(['a', 'b', 'c']);

x.forEach(function(value) {

console.dir(value);

});

</example>

Spec:

http://www.ecma-international.org/ecma-262/6.0/#sec-set.prototype.forEach

----

prototype.has(value : Object) : Boolean

Returns **true** if the set contains **value**.

<example>

var x = new Set(['a', 'b', 'c']);

console.log(x.has('a'));

console.log(x.has('foo'));

</example>

Spec:

http://www.ecma-international.org/ecma-262/6.0/#sec-set.prototype.has

----

prototype.keys() : Iterator

Same as %%#values|values()%%.

Spec:

http://www.ecma-international.org/ecma-262/6.0/#sec-set.prototype.keys

----

prototype.values() : Iterator

Returns an iterator of the values in **this**.

The **values** function is also returned for

**this[%%/Symbol#iterator|Symbol.iterator%%]** so you can

iterate over **this** directly to get the values.

See also %%#entries|**entries()**%% and %%#keys|**keys()**%%.

<example>

var x = new Set(['a', 'b', 'c']);

// values is returned by x[Symbol.iterator] so you can just

// use x directly in the for (... of ...) loop

for (var value of x) {

console.dir(value);

}

// You can iterate over values explicitly

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

console.dir(value);

}

// Or access the iterator manually

var values = x.values();

console.dir(values.next());

console.dir(values.next());

console.dir(values.next());

console.dir(values.next());

</example>

Spec:

http://www.ecma-international.org/ecma-262/6.0/#sec-set.prototype.values