The class declaration creates a new class with a given name using prototype-based inheritance.
You can also define a class using a class expression.
class name [extends] {
// class body
}
Just like with class expressions, the class body of a class declaration is executed in strict mode.
Class declarations are not hoisted (unlike function declarations).
In the following example, we first define a class named Polygon, then extend it to create a class named Square. Note that super(), used in the constructor, can only be used in constructors and must be called before the this keyword can be used.
class Polygon {
constructor(height, width) {
this.name = 'Polygon';
this.height = height;
this.width = width;
}
}
class Square extends Polygon {
constructor(length) {
super(length, length);
this.name = 'Square';
}
}
Created by Mozilla Contributors, license: CC-BY-SA 2.5