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JavaScript extend multiple classes | Code

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Use the Mix-ins concept to extend multiple classes in JavaScript. A JS class can only have a single superclass, so multiple inheritances from child classes are not possible. The functionality must be provided by the superclass.

A function with a superclass as input and a subclass extending that superclass as output can be used to implement mix-ins.

let calculatorMixin = Base => class extends Base {
  calc() { }

let randomizerMixin = Base => class extends Base {
  randomize() { }

A class that uses these mix-ins can then be written like this:

class Foo { }
class Bar extends calculatorMixin(randomizerMixin(Foo)) { }

JavaScript extends multiple classes

Simple example code.

<!DOCTYPE html>
    class Parent {
      someParentMethod () {

   class ChildOne extends Parent {
     someChildOneMethod () {

   class ChildTwo extends Parent {
     someChildTwoMethod () {

    // define GrandChild as a Mix-in:
    let GrandChild = Base => class extends Base {
      someGrandChildMethod() {

    class GrandChildOne extends GrandChild(ChildOne) { }
    class GrandChildTwo extends GrandChild(ChildTwo) { }

    const grandChildOne = new GrandChildOne()
    const grandChildTwo = new GrandChildTwo()





Do comment if you have any doubts or suggestions on this Js class topic.

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

OS: Windows 10

Code: HTML 5 Version

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