Set.prototype.isDisjointFrom()
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 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
isDisjointFrom(other)
Parameters
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:
And using Venn diagram:
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
thanother.size
, then it iterates overother
by calling itskeys()
method, and if any element inother
is present inthis
, it returnsfalse
(and closes thekeys()
iterator by calling itsreturn()
method). Otherwise, it returnstrue
. - Otherwise, it iterates over the elements in
this
, and returnsfalse
if any elemente
inthis
causesother.has(e)
to return a truthy value. Otherwise, it returnstrue
.
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:
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:
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
Specification |
---|
Set methods # sec-set.prototype.isdisjointfrom |
Browser compatibility
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