The Map[@@species]
accessor property returns the Map
constructor.
Syntax
Map[Symbol.species]
Description
The species accessor property returns the default constructor for Map
objects. Subclass constructors may over-ride it to change the constructor assignment.
Examples
The species property returns the default constructor function, which is the Map
constructor for Map
objects:
Map[Symbol.species]; // function Map()
In a derived collection object (e.g. your custom map MyMap
), the MyMap
species is the MyMap
constructor. However, you might want to overwrite this, in order to return parent Map
objects in your derived class methods:
class MyMap extends Map { // Overwrite MyMap species to the parent Map constructor static get [Symbol.species]() { return Map; } }
Specifications
Specification | Status | Comment |
---|---|---|
ECMAScript 2015 (6th Edition, ECMA-262) The definition of 'get Map [ @@species ]' in that specification. |
Standard | Initial definition. |
ECMAScript Latest Draft (ECMA-262) The definition of 'get Map [ @@species ]' in that specification. |
Living Standard |
Browser compatibility
The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
Feature | Chrome | Edge | Firefox | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|---|
Basic support | 51 | 13 | 41 | No | 38 | 10 |
Feature | Android webview | Chrome for Android | Edge mobile | Firefox for Android | IE mobile | Opera Android | iOS Safari |
---|---|---|---|---|---|---|---|
Basic support | 51 | 51 | 13 | 41 | No | 38 | 10 |