Set[Symbol.species] - JavaScript | MDN
Syntax
Return value
The value of the constructor (this) on which get [Symbol.species] was called. The return value is used to construct copied Set instances.
Description
The [Symbol.species] accessor property returns the default constructor for Set objects. Subclass constructors may override it to change the constructor assignment.
Note:
This property is currently unused by all Set methods.
Examples
Species in ordinary objects
The [Symbol.species] property returns the default constructor function, which is the Set constructor for Set.
js
Set[Symbol.species]; // function Set()
Species in derived objects
In an instance of a custom Set subclass, such as MySet, the MySet species is the MySet constructor. However, you might want to overwrite this, in order to return parent Set objects in your derived class methods:
js
class MySet extends Set {
// Overwrite MySet species to the parent Set constructor
static get [Symbol.species]() {
return Set;
}
}
Specifications
| Specification |
|---|
| ECMAScript® 2027 Language Specification # sec-get-set-%symbol.species% |