Set.prototype.intersection()
Baseline 2024
Newly available
Since June 2024, this feature works across the latest devices and browser versions. This feature might not work in older devices or browsers.
The intersection()
method of Set
instances takes a set and returns a new set containing elements in both this set and the given set.
Syntax
intersection(other)
Parameters
Return value
A new Set
object containing elements in both this set and the other
set.
Description
In mathematical notation, intersection is defined as:
And using Venn diagram:
intersection()
accepts set-like objects as the other
parameter. It requires this
to be an actual Set
instance, because it directly retrieves the underlying data stored in this
without invoking any user code. Then, its behavior depends on the sizes of this
and other
:
- If there are more elements in
this
thanother.size
, then it iterates overother
by calling itskeys()
method, and constructs a new set with all elements produced that are also present inthis
. - Otherwise, it iterates over the elements in
this
, and constructs a new set with all elementse
inthis
that causeother.has(e)
to return a truthy value.
Because of this implementation, the efficiency of intersection()
mostly depends on the size of the smaller set between this
and other
(assuming sets can be accessed in sublinear time). The order of elements in the returned set is the same as that of the smaller of this
and other
.
Examples
Using intersection()
The following example computes the intersection between the set of odd numbers (<10) and the set of perfect squares (<10). The result is the set of odd numbers that are perfect squares.
const odds = new Set([1, 3, 5, 7, 9]);
const squares = new Set([1, 4, 9]);
console.log(odds.intersection(squares)); // Set(2) { 1, 9 }
Specifications
Specification |
---|
Set methods # sec-set.prototype.intersection |
Browser compatibility
BCD tables only load in the browser