This article is in need of a technical review.
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.
Draft
This page is not complete.
Summary
Starting with ECMASCript 6, a new syntax for class definitions is introduced. Although the syntax looks like the syntax of languages with class-based inheritance, JavaScript remains prototype-based.
Syntax
The class keyword has two forms, a declaration form and an expression form.
//declaration form
class className {
//Class body
};
// expression form
const MyClass = class className {
//Class body
};
Example
"use strict";
class Polygon {
constructor(height, width) {
this.height = height;
this.width = width;
}
}
class Square extends Polygon {
constructor(sideLength) {
super(sideLength, sideLength);
}
get area() {
return this.height * this.width;
}
set sideLength(newLength) {
this.height = newLength;
this.width = newLength;
}
}
var square = new Square(2);
Specifications
| Specification | Status | Comment |
|---|---|---|
| ECMAScript 6 (ECMA-262) The definition of 'Class definitions' in that specification. |
Release Candidate | Initial definition. |
Browser compatibility