Skip to content

JavaScript extends | keyword

  • by

The extends keyword can be used to extend the objects as well as classes in JavaScript. The extends keyword can be used to subclass custom classes as well as built-in objects. In another word, its used to create a class that is a child of another class.

class childclass extends parentclass {

class parentclass extends in-built object {

JavaScript extends

Simple example code.

JavaScript extends class

inherit the methods from the “Car” class:

<!DOCTYPE html>
    class Car {
      constructor(brand) {
        this.carname = brand;
      present() {
        return 'I have a ' + this.carname;

    class Model extends Car {
      constructor(brand, mod) {
        this.model = mod;
      show() {
        return this.present() + ', it is a ' + this.model;

    mycar = new Model("AUDI", "Q7");



JavaScript extends

Using extends object

This example extends the built-in Date object.

    class myDate extends Date {

      getFormattedDate() {
        var months = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'];
        return this.getDate() + '-' + months[this.getMonth()] + '-' + this.getFullYear();

    var d = new myDate()




Do comment if you have any doubts or suggestions on this JS extends keyword.

Note: The All JS Examples codes are tested on the Firefox browser and the Chrome browser.

OS: Windows 10

Code: HTML 5 Version

Leave a Reply

Your email address will not be published. Required fields are marked *