Set.prototype[Symbol.iterator]()
Baseline
Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since September 2015.
The [Symbol.iterator]() method of Set instances implements the iterable protocol and allows Set objects to be consumed by most syntaxes expecting iterables, such as the spread syntax and for...of loops. It returns a set iterator object that yields the values of the set in insertion order.
The initial value of this property is the same function object as the initial value of the Set.prototype.values property.
Try it
const set = new Set();
set.add(42);
set.add("forty two");
const iterator = set[Symbol.iterator]();
console.log(iterator.next().value);
// Expected output: 42
console.log(iterator.next().value);
// Expected output: "forty two"
Syntax
set[Symbol.iterator]()
Parameters
None.
Return value
The same return value as Set.prototype.values(): a new iterable iterator object that yields the values of the set.
Examples
Iteration using for...of loop
Note that you seldom need to call this method directly. The existence of the [Symbol.iterator]() method makes Set objects iterable, and iterating syntaxes like the for...of loop automatically call this method to obtain the iterator to loop over.
const mySet = new Set();
mySet.add("0");
mySet.add(1);
mySet.add({});
for (const v of mySet) {
console.log(v);
}
Manually hand-rolling the iterator
You may still manually call the next() method of the returned iterator object to achieve maximum control over the iteration process.
const mySet = new Set();
mySet.add("0");
mySet.add(1);
mySet.add({});
const setIter = mySet[Symbol.iterator]();
console.log(setIter.next().value); // "0"
console.log(setIter.next().value); // 1
console.log(setIter.next().value); // {}
Specifications
| Specification |
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| ECMAScript® 2027 Language Specification # sec-set.prototype-%symbol.iterator% |
Browser compatibility
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Legend
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- Full support
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- Uses a non-standard name
- Has more compatibility info.