Set.@@species

The Set[@@species] accessor property returns the Set constructor.

Syntax

Set[Symbol.species]

Description

The species accessor property returns the default constructor for Set objects. Subclass constructors may over-ride it to change the constructor assignment.

Examples

The species property returns the default constructor function, which is the Set constructor for Set objects:

Set[Symbol.species]; // function Set()

In a derived collection object (e.g. your custom set 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:

class MySet extends Set {
  // Overwrite MySet species to the parent Set constructor
  static get [Symbol.species]() { return Set; }
}

Specifications

Specification	Status	Comment
ECMAScript 2015 (6th Edition, ECMA-262) The definition of 'get Set [ @@species ]' in that specification.	Standard	Initial definition.
ECMAScript 2017 Draft (ECMA-262) The definition of 'get Set [ @@species ]' in that specification.	Draft

Browser compatibility

See also

• Set
• Symbol.species