Newly availableA good fit when your code already models state as sets and needs clear relationship checks between them.
Map and Set Newly available

Set methods

The modern Set methods add built-in operations such as union(), intersection(), difference(), and subset checks. They make mathematical set logic easier to express directly.

Map and SetSet operationsES2024

Overview

The modern Set methods add built-in operations such as union(), intersection(), difference(), and subset checks. They make mathematical set logic easier to express directly.

Browser support

Feature Desktop Mobile
Chrome
Edge
Firefox
Safari
Chrome Android
Safari iOS
javascript.builtins.Set.difference
122
122
127
17
122
17
Built-in object
Set.intersection

The intersection() method of Set instances takes a set and returns a new set containing elements in both this set and the given set.
122
122
127
17
122
17
Set.isDisjointFrom

The isDisjointFrom() method of Set instances takes a set and returns a boolean indicating if this set has no elements in common with the given set.
122
122
127
17
122
17
Set.isSubsetOf

The isSubsetOf() method of Set instances takes a set and returns a boolean indicating if all elements of this set are in the given set.
122
122
127
17
122
17
Set.isSupersetOf

The isSupersetOf() method of Set instances takes a set and returns a boolean indicating if all elements of the given set are in this set.
122
122
127
17
122
17
Set.symmetricDifference

The symmetricDifference() method of Set instances takes a set and returns a new set containing elements which are in either this set or the given set, but not in both.
122
122
127
17
122
17
Set.union

The union() method of Set instances takes a set and returns a new set containing elements which are in either or both of this set and the given set.
122
122
127
17
122
17
1+Supported (version) Not supported ※Has note Sub-feature descriptions sourced from MDN Web Docs (CC BY-SA 2.5)

Syntax

JAVASCRIPT 
const a = new Set([1, 2, 3, 4]);
const b = new Set([3, 4, 5, 6]);

a.union(b);              // Set {1, 2, 3, 4, 5, 6}
a.intersection(b);       // Set {3, 4}
a.difference(b);         // Set {1, 2}
a.symmetricDifference(b); // Set {1, 2, 5, 6}
a.isSubsetOf(b);         // false
a.isSupersetOf(b);       // false

Live demo

collectioncombine. Union (union)

2. collectioncombine unified, all. Duplicates element read..

PreviewFullscreen

commonpartial. Extract (intersection)

2. collectioncombine. both to includeelement(commonskil etc) extract..

PreviewFullscreen

Difference. Extract (difference)

oneside. collectioncombine to with, otherside to is element(not-aitemu etc) extract..

PreviewFullscreen

Use cases

  • Combining selections

    Use union or difference to merge active filters, permissions, or selected IDs without duplicate logic.

  • Permission comparisons

    Subset and superset checks make authorization and capability comparisons much clearer.

Cautions

  • These APIs are newer than classic Set basics, so verify support targets or keep a polyfill strategy if needed.
  • Set equality is still based on value identity rules, so object members are compared by reference.

Accessibility

  • If set operations control visible selections, keep the selected state explicit in both visuals and assistive text.

Related links

Powered by web-features