The well-known symbol Symbol.species
specifies a function-valued property that the constructor function uses to create derived objects.
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Description
The species accessor property allows subclasses to override the default constructor for objects.
Property attributes of Symbol.species |
|
---|---|
Writable | no |
Enumerable | no |
Configurable | no |
Examples
Using species
You might want to return Array
objects in your derived array class MyArray
. For example, when using methods such as map()
that return the default constructor, you want these methods to return a parent Array
object, instead of the MyArray
object. The species symbol lets you do this:
class MyArray extends Array { // Overwrite species to the parent Array constructor static get [Symbol.species]() { return Array; } } let a = new MyArray(1,2,3); let mapped = a.map(x => x * x); console.log(mapped instanceof MyArray); // false console.log(mapped instanceof Array); // true
Specifications
Specification |
---|
ECMAScript (ECMA-262) The definition of 'Symbol.species' in that specification. |
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.
Desktop | Mobile | Server | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
species | Chrome Full support 51 | Edge Full support 13 | Firefox Full support 41 | IE No support No | Opera Full support 38 | Safari Full support 10 | WebView Android Full support 51 | Chrome Android Full support 51 | Firefox Android Full support 41 | Opera Android Full support 41 | Safari iOS Full support 10 | Samsung Internet Android Full support 5.0 | nodejs
Full support
6.5.0
|
Legend
- Full support
- Full support
- No support
- No support
- User must explicitly enable this feature.
- User must explicitly enable this feature.