Flash cards
Review the key moves
What is the main idea behind JavaScript Set Logic?
Lesson checks
Practice each idea before moving on
Short Mimo-style checks built from this lesson's code, terms, and sequence.
Which statement best captures the main point of this lesson?
Complete the missing token from the example code.
___ A = new Set(['a','b','c']);Put the learning moves in the order that makes the concept easiest to apply.
| Logic Set Methods In JavaScript 2025, 7 new logical methods were added to the Set object: union() difference() intersection() isDisjointFrom() isSubsetOf() isSupersetOf() symmetricDifference() |
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Browser Support
Set Logic is an ECMAScript 2025 feature.
JavaScript 2025 is fully supported in all modern browsers since May 2025 :
| Chrome 136 | Edge 136 | Firefox 129 | Safari 18.2 | Opera 120 |
|---|---|---|---|---|
| Apr 2025 | Apr 2025 | Aug 2024 | Des 2024 | May 2025 |
The union() Method
The union() method returns the union of two sets.
The union() method returns a new set containing the elements which are in this set, or in the argument set, or in both:
Example
const A = new Set(['a','b','c']);
const B = new Set(['b','c','d']);
const C = A.union(B);The intersection() Method
The intersection() method returns the intersection of two sets.
The intersection() method returns a new set containing the elements which are in this set and in the argument set:
Example
const A = new Set(['a','b','c']);
const B = new Set(['b','c','d']);
const C = A.intersection(B);The difference() Method
The difference() method returns the difference between two sets.
The difference() method returns a new set containing elements which are in this set but not in the argument set:
Example
const A = new Set(['a','b','c']);
const B = new Set(['b','c','d']);
const C = A.difference(B);The symmetricDifference() Method
The symmetricDifference() method returns the symmetric difference between to sets.
The symmetricDifference() method returns a new set containing elements which are in this set or in the argument set, but not in both:
Example
const A = new Set(['a','b','c']);
const B = new Set(['b','c','d']);
const C = A.symmetricDifference(B);The isSubsetOf() Method
The isSubsetOf() method returns true if all elements in this set is also elements in the argument set:
Example
const A = new Set(['a','b','c']);
const B = new Set(['b','c','d']);
let answer = A.isSubsetOf(B);The isSupersetOf() Method
The isSupersetOf() method returns true if all elements in the argument set are also in this set:
Example
const A = new Set(['a','b','c']);
const B = new Set(['b','c','d']);
let answer = A.isSupersetOf(B);The isDisjointFrom() Method
The isDisjointFrom() method returns true if this set has no elements in common with the argument set:
Example
const A = new Set(['a','b','c']);
const B = new Set(['b','c','d']);
let answer = A.isDisjointFrom(B);Learn More
JavaScript Sets
JavaScript Set Methods
JavaScript Weak Sets
JavaScript Set Reference
JavaScript Maps