This is an experimental technology, part of the ECMAScript 6 (Harmony) proposal.
Because this technology's specification has not stabilized, check the compatibility table for usage in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future version of browsers as the spec changes.
The super keyword is used to call functions on an object's parent.
The super.prop
and super[expr]
expressions are valid in any method definition in both classes and object literals.
Syntax
super([arguments]); // calls the parent constructor. super.functionOnParent([arguments]);
Description
When used in a constructor, the super
keyword appears alone and must be used before the this
keyword can be used. This keyword can also be used to call to call functions on a parent object.
Example
This code snippet is taken from the classes sample (live demo).
class Square extends Polygon { constructor(length) { // Here, it calls the parent class' constructor with lengths // provided for the Polygon's width and height super(length, length); // Note: In derived classes, super() must be called before you // can use 'this'. Leaving this out will cause a reference error. this.name = 'Square'; } get area() { return this.height * this.width; } set area(value) { this.area = value; } }
Specifications
Specification | Status | Comment |
---|---|---|
ECMAScript 6 (ECMA-262) The definition of 'super' in that specification. |
Release Candidate | Initial definition. |
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|
Basic support | 42.0 | Not supported bug 1066239 |
? | ? | ? |
Feature | Android | Chrome for Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | |
---|---|---|---|---|---|---|
Basic support | ? | 42.0 | Not supported bug 1066239 |
? | ? | ? |