The Map[@@species]
static accessor property is an unused accessor property specifying how to copy Map
objects.
The Map[@@species]
static accessor property is an unused accessor property specifying how to copy Map
objects.
Map[Symbol.species]
The value of the constructor (this
) on which get @@species
was called. The return value is used to construct copied Map
instances.
The @@species
accessor property returns the default constructor for Map
objects. Subclass constructors may override it to change the constructor assignment.
Note: This property is currently unused by all Map
methods.
The @@species
property returns the default constructor function, which is the Map
constructor for Map
.
Map[Symbol.species]; // function Map()
In an instance of a custom Map
subclass, such as 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; } }
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 | ||
@@species |
51 | 13 | 41 | 38 | 10 | 51 | 41 | 41 | 10 | 5.0 | 51 | 1.0 | 6.5.0 |
© 2005–2023 MDN contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/@@species