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Set.prototype.isDisjointFrom()

Limited availability

This feature is not Baseline because it does not work in some of the most widely-used browsers.

Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

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.

Syntax

js
isDisjointFrom(other)

Parameters

other

A Set object, or set-like object.

Return value

true if this set has no elements in common with the other set, and false otherwise.

Description

Two sets are disjoint if they have no elements in common. In mathematical notation:

A is disjoint from B A B = A\text{ is disjoint from }B \Leftrightarrow A\cap B = \empty

And using Venn diagram:

A Venn diagram with two circles. A and B are disjoint because the circles have no region of overlap.

isDisjointFrom() 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 than other.size, then it iterates over other by calling its keys() method, and if any element in other is present in this, it returns false (and closes the keys() iterator by calling its return() method). Otherwise, it returns true.
  • Otherwise, it iterates over the elements in this, and returns false if any element e in this causes other.has(e) to return a truthy value. Otherwise, it returns true.

Because of this implementation, the efficiency of isDisjointFrom() mostly depends on the size of the smaller set between this and other (assuming sets can be accessed in sublinear time).

Examples

Using isDisjointFrom()

The set of perfect squares (<20) is disjoint from the set of prime numbers (<20), because a perfect square is by definition decomposable into the product of two integers, while 1 is also not considered a prime number:

js
const primes = new Set([2, 3, 5, 7, 11, 13, 17, 19]);
const squares = new Set([1, 4, 9, 16]);
console.log(primes.isDisjointFrom(squares)); // true

The set of perfect squares (<20) is not disjoint from the set of composite numbers (<20), because all non-1 perfect squares are by definition composite numbers:

js
const composites = new Set([4, 6, 8, 9, 10, 12, 14, 15, 16, 18]);
const squares = new Set([1, 4, 9, 16]);
console.log(composites.isDisjointFrom(squares)); // false

Specifications

Browser compatibility

Desktop Mobile Server
Chrome Edge Firefox Opera Safari Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet WebView Android Deno Node.js
isDisjointFrom No No preview No 17 No No No 17 No No No No

See also

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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Set/isDisjointFrom