āĻ•ā§āϞāĻžāϏ āĻŦāĻžāĻĄāĻŧāĻžāύ

extends āϕ⧀āĻ“āϝāĻŧāĻžāĻ°ā§āĻĄāϟāĻŋ āĻ•ā§āϞāĻžāϏ āĻĄāĻŋāĻ•ā§āϞ⧇āϝāĻŧāĻžāϰ⧇āĻļāύ āĻŦāĻž āĻāĻ•ā§āϏāĻĒā§āϰ⧇āĻļāύ⧇ āĻŦā§āϝāĻŦāĻšāĻžāϰ āĻ•āϰāĻž āĻšāϝāĻŧ āĻāĻŽāύ āĻāĻ•āϟāĻŋ āĻ•ā§āϞāĻžāϏ āϤ⧈āϰāĻŋ āĻ•āϰāϤ⧇ āϝāĻž āĻ…āĻ¨ā§āϝ āĻāĻ•āϟāĻŋ āϏāĻžāĻŦāĻ•ā§āϞāĻžāϏ āĻšāĻŋāϏ⧇āĻŦ⧇ āĻ•āĻžāϜ āĻ•āϰ⧇, āϝāĻžāϰ āϏāĻžāĻĨ⧇ āĻĒā§āϝāĻžāϰ⧇āĻ¨ā§āϟ āĻ•ā§āϞāĻžāϏ (āĻ•āĻ–āύāĻ“ āĻ•āĻ–āύāĻ“ "āĻŦ⧇āϏ āĻ•ā§āϞāĻžāϏ" āĻŦāϞāĻž āĻšāϝāĻŧ) āĻļāĻŋāĻļ⧁ āĻļā§āϰ⧇āĻŖā§€āϰ (āĻ•āĻ–āύāĻ“ āĻ•āĻ–āύāĻ“ "āϏāĻžāĻŦāĻ•ā§āϞāĻžāϏ" āĻŦāϞāĻž āĻšāϝāĻŧ) āĻāϰ āĻĒā§āϰ⧋āĻŸā§‹āϟāĻžāχāĻĒ āĻšāĻŋāϏāĻžāĻŦ⧇ āĻ•āĻžāϜ āĻ•āϰ⧇āĨ¤ āĻŦāĻž "āωāĻ¤ā§āĻĒāĻ¨ā§āύ āĻļā§āϰ⧇āĻŖā§€")āĨ¤

class ParentClass {}
class ChildClass extends ParentClass {}

Object.getPrototypeOf( ChildClass );
> class ParentClass {}

āĻāχ āϏāĻžāĻŦāĻ•ā§āϞāĻžāϏāϗ⧁āϞāĻŋ āĻĒā§āϝāĻžāϰ⧇āĻ¨ā§āϟ āĻ•ā§āϞāĻžāϏ⧇āϰ āĻŦ⧈āĻļāĻŋāĻˇā§āĻŸā§āϝ āĻāĻŦāĻ‚ āĻĒāĻĻā§āϧāϤāĻŋāϰ āωāĻ¤ā§āϤāϰāĻžāϧāĻŋāĻ•āĻžāϰ⧀ āĻšāϝāĻŧāĨ¤ āĻāϟāĻŋ āφāĻĒāύāĻžāϕ⧇ āĻĒā§āϰāϤāĻŋāϟāĻŋ āϏāĻŽā§āĻ­āĻžāĻŦā§āϝ āĻŦā§āϝāĻŦāĻšāĻžāϰ⧇āϰ āĻ•ā§āώ⧇āĻ¤ā§āϰ⧇ āĻĒā§āϝāĻžāϰ⧇āĻ¨ā§āϟ āĻ•ā§āϞāĻžāϏāϕ⧇ āĻ“āĻ­āĻžāϰāϞ⧋āĻĄ āύāĻž āĻ•āϰ⧇ āφāϰāĻ“ āύāĻŋāĻ°ā§āĻĻāĻŋāĻˇā§āϟ āωāĻĻā§āĻĻ⧇āĻļā§āϝāϗ⧁āϞāĻŋ āĻĒāϰāĻŋāĻŦ⧇āĻļāύ āĻ•āϰāĻžāϰ āϜāĻ¨ā§āϝ āĻāĻ•āϟāĻŋ āĻ•ā§āϞāĻžāϏ⧇āϰ āĻŽā§‚āϞ āĻ•āĻžāĻ°ā§āϝāĻ•āĻžāϰāĻŋāϤāĻž āĻĒā§āϰāϏāĻžāϰāĻŋāϤ āĻ•āϰāϤ⧇ āĻĻ⧇āϝāĻŧ, āĻŦāĻž āĻāĻ•āχ āωāĻĻā§āĻĻ⧇āĻļā§āϝ⧇ āĻ•āĻžāϜ āĻ•āϰ⧇ āĻāĻŽāύ āϕ⧋āĻĄ āĻĒ⧁āύāϰāĻžāϝāĻŧ āĻĒā§āϰāϝāĻŧā§‹āĻ— āĻ•āϰāĻžāĨ¤

āĻļāĻŋāĻļ⧁ āĻļā§āϰ⧇āĻŖā§€āϗ⧁āϞāĻŋ āĻāĻ•āϟāĻŋ āĻ…āĻ­āĻŋāĻ­āĻžāĻŦāĻ• āĻļā§āϰ⧇āĻŖā§€āϰ āĻĨ⧇āϕ⧇ āωāĻ¤ā§āϤāϰāĻžāϧāĻŋāĻ•āĻžāϰāϏ⧂āĻ¤ā§āϰ⧇ āĻĒā§āϰāĻžāĻĒā§āϤ āĻĒāĻĻā§āϧāϤāĻŋāϗ⧁āϞāĻŋāϰ āύāĻŋāϜāĻ¸ā§āĻŦ āĻŦāĻžāĻ¸ā§āϤāĻŦāĻžāϝāĻŧāύ āĻĒā§āϰāĻĻāĻžāύ āĻ•āϰāϤ⧇ āĻĒāĻžāϰ⧇:

class MyClass {
  constructor( myPassedValue ) {
    this.instanceProp = myPassedValue;
  }
  classMethod() {
    console.log( `The value was '${ this.instanceProp }.'`)
  }
}
class ChildClass extends MyClass {
  classMethod() {
    console.log( `The value was '${ this.instanceProp },' and its type was '${ typeof this.instanceProp }.'`)
  }
}

const myParentClassInstance = new MyClass( "My string." );
const mySubclassInstance = new ChildClass( 100 );

myParentClassInstance.classMethod();
> "The value type was 'string.'"

mySubclassInstance.classMethod();
> "The value was '100,' and its type was 'number.'"

āφāĻĒāύāĻŋ super āĻŦā§āϝāĻŦāĻšāĻžāϰ āĻ•āϰ⧇ āϚāĻžāχāĻ˛ā§āĻĄ āĻ•ā§āϞāĻžāϏ⧇āϰ āĻĒā§āϰāϏāĻ™ā§āϗ⧇ āĻ…āĻ­āĻŋāĻ­āĻžāĻŦāĻ• āĻļā§āϰ⧇āĻŖāĻŋāϤ⧇ āϏāĻ‚āĻœā§āĻžāĻžāϝāĻŧāĻŋāϤ āĻĒāĻĻā§āϧāϤāĻŋāϗ⧁āϞāĻŋāϕ⧇ āĻ•āϞ āĻ•āϰāϤ⧇ āĻĒāĻžāϰ⧇āύ:

class MyClass {
  constructor( myPassedValue ) {
    this.instanceProp = myPassedValue;
  }
  classMethod() {
    console.log( `The value was '${ this.instanceProp }.'`)
  }
}

class ChildClass extends MyClass {
  subclassMethod() {
    super.classMethod();
    console.log( `The value type was '${ typeof this.instanceProp }.'`)
  }
}
const mySubclassInstance = new ChildClass( 100 );

mySubclassInstance.subclassMethod();
> The value was '100.'
> The value type was 'number.'

āĻĒā§‚āĻ°ā§āĻŦāĻŦāĻ°ā§āϤ⧀ āωāĻĻāĻžāĻšāϰāĻŖāϗ⧁āϞāĻŋāϤ⧇ āĻĻ⧇āĻ–āĻž āϗ⧇āϛ⧇, āϝāĻ–āύ āĻāĻ•āϟāĻŋ āĻļāĻŋāĻļ⧁ āĻļā§āϰ⧇āĻŖā§€āϰ āĻĒā§āϰ⧇āĻ•ā§āώāĻžāĻĒāĻŸā§‡ constructor() āĻĒāĻĻā§āϧāϤāĻŋāϟāĻŋ āĻŦāĻžāĻĻ āĻĻ⧇āĻ“āϝāĻŧāĻž āĻšāϝāĻŧ, āϤāĻ–āύ āϜāĻžāĻ­āĻžāĻ¸ā§āĻ•ā§āϰāĻŋāĻĒā§āĻŸā§‡āϰ āĻ…āĻ¨ā§āϤāĻ°ā§āύāĻŋāĻšāĻŋāϤ āĻ•āĻ¨ā§āϏāĻŸā§āϰāĻžāĻ•ā§āϟāϰ āĻāĻ•āχ āφāĻ°ā§āϗ⧁āĻŽā§‡āĻ¨ā§āĻŸā§‡āϰ āϏāĻžāĻĨ⧇ āĻĒā§āϝāĻžāϰ⧇āĻ¨ā§āϟ āĻ•āύāĻ¸ā§āĻŸā§āϰāĻžāĻ•ā§āϟāϰāϕ⧇ āĻ•āϞ āĻ•āϰ⧇āĨ¤ āϝāĻžāχāĻšā§‹āĻ•, āϝāĻĻāĻŋ āϏāĻžāĻŦāĻ•ā§āϞāĻžāϏ⧇ āϕ⧋āύ āĻ•āύāĻ¸ā§āĻŸā§āϰāĻžāĻ•ā§āϟāϰ āĻĨāĻžāϕ⧇, āϤāĻžāĻšāϞ⧇ this āωāĻ˛ā§āϞ⧇āĻ– āĻ•āϰāĻžāϰ āφāϗ⧇ āĻĒā§āϰāĻĨāĻŽā§‡ super() āϝ⧇āϕ⧋āύ⧋ āĻĒā§āϰāϝāĻŧā§‹āϜāύ⧀āϝāĻŧ āφāĻ°ā§āϗ⧁āĻŽā§‡āĻ¨ā§āϟ āϏāĻš āĻ•āϞ ​​āĻ•āϰāϤ⧇ āĻšāĻŦ⧇āĨ¤

class MyClass {
  constructor( myPassedValue ) {
    this.instanceProp = myPassedValue;
  }
  classMethod() {
    console.log( `The value was '${ this.instanceProp }.'`)
  }
}

class ChildClass extends MyClass {
    constructor( myPassedValue ) {
        super( myPassedValue );
        this.modifiedProp = myPassedValue + 50;
    }\
    subclassMethod() {
        super.classMethod();
        console.log( `The value type was '${ typeof this.instanceProp }.'`)
    }
}
const mySubclassInstance = new ChildClass( 100 );

mySubclassInstance;
> MyClass { instanceProp: 100, modifiedProp: 150 }

Getters āĻāĻŦāĻ‚ setters āĻšāϞ āĻŦāĻŋāĻļ⧇āώ āĻĒāĻĻā§āϧāϤāĻŋ āϝāĻž āϝāĻĨāĻžāĻ•ā§āϰāĻŽā§‡ āĻĒ⧁āύāϰ⧁āĻĻā§āϧāĻžāϰ āĻāĻŦāĻ‚ āϏāĻ‚āĻœā§āĻžāĻžāϝāĻŧāĻŋāϤ āĻ•āϰāĻžāϰ āϜāĻ¨ā§āϝ āĻāĻ•āĻšā§‡āϟāĻŋāϝāĻŧāĻžāĻ­āĻžāĻŦ⧇ āĻŦā§āϝāĻŦāĻšā§ƒāϤ āĻšāϝāĻŧāĨ¤ get āĻāĻŦāĻ‚ set āϕ⧀āĻ“āϝāĻŧāĻžāĻ°ā§āĻĄ āĻŦā§āϝāĻŦāĻšāĻžāϰ āĻ•āϰ⧇ āϏāĻ‚āĻœā§āĻžāĻžāϝāĻŧāĻŋāϤ āĻĒāĻĻā§āϧāϤāĻŋāϗ⧁āϞāĻŋ āφāĻĒāύāĻžāϕ⧇ āĻāĻŽāύ āĻĒāĻĻā§āϧāϤāĻŋ āϤ⧈āϰāĻŋ āĻ•āϰāϤ⧇ āĻĻ⧇āϝāĻŧ āϝ⧇āϗ⧁āϞāĻŋāϰ āϏāĻžāĻĨ⧇ āχāĻ¨ā§āϟāĻžāϰāĻ…ā§āϝāĻžāĻ•ā§āϟ āĻ•āϰāĻž āϝ⧇āϤ⧇ āĻĒāĻžāϰ⧇ āϝ⧇āύ āϏ⧇āϗ⧁āϞāĻŋ āĻ¸ā§āĻŸā§āϝāĻžāϟāĻŋāĻ• āĻŦ⧈āĻļāĻŋāĻˇā§āĻŸā§āϝāĨ¤

class MyClass {
    constructor( originalValue ) {
        this.totalValue = 0;
    }
    set doubleThisValue( newValue ) {
        this.totalValue = newValue * 2;
    }
    get currentValue() {
        console.log( `The current value is: ${ this.totalValue }` );
    }
}
const myClassInstance = new MyClass();

myClassInstance;
> MyClass { totalValue: 0 }

myClassInstance.doubleThisValue = 20;

myClassInstance.currentValue;
> The current value is: 40

get āĻāĻŦāĻ‚ set āĻŦ⧈āĻļāĻŋāĻˇā§āĻŸā§āϝāϗ⧁āϞāĻŋ āĻ•ā§āϞāĻžāϏ⧇āϰ āĻĒā§āϰ⧋āĻŸā§‹āϟāĻžāχāĻĒ āϏāĻŽā§āĻĒāĻ¤ā§āϤāĻŋāϤ⧇ āϏāĻ‚āĻœā§āĻžāĻžāϝāĻŧāĻŋāϤ āĻ•āϰāĻž āĻšāϝāĻŧ āĻāĻŦāĻ‚ āϤāĻžāχ āĻ•ā§āϞāĻžāϏ⧇āϰ āϏāĻŽāĻ¸ā§āϤ āωāĻĻāĻžāĻšāϰāϪ⧇āϰ āϜāĻ¨ā§āϝ āωāĻĒāϞāĻŦā§āϧāĨ¤

āφāĻĒāύāĻžāϰ āωāĻĒāϞāĻŦā§āϧāĻŋ āĻĒāϰ⧀āĻ•ā§āώāĻž āĻ•āϰ⧁āύ

extends āϕ⧀āĻ“āϝāĻŧāĻžāĻ°ā§āĻĄ āĻĻāĻŋāϝāĻŧ⧇ āϤ⧈āϰāĻŋ āĻ•ā§āϞāĻžāϏ āϏāĻŽā§āĻĒāĻ°ā§āϕ⧇ āϏāĻ¤ā§āϝ āĻŦāĻŋāĻŦ⧃āϤāĻŋ āύāĻŋāĻ°ā§āĻŦāĻžāϚāύ āĻ•āϰ⧁āύāĨ¤

āĻāϟāĻŋ āĻĒā§āϰāϏāĻžāϰāĻŋāϤ āĻ•ā§āϞāĻžāϏ⧇āϰ āϏāĻ¨ā§āϤāĻžāύ āĻšāĻŋāϏāĻžāĻŦ⧇ āĻ•āĻžāϜ āĻ•āϰ⧇āĨ¤
āĻāϟāĻŋ āĻāϰ āĻŽā§‚āϞ āĻļā§āϰ⧇āĻŖā§€āϰ āĻŦ⧈āĻļāĻŋāĻˇā§āĻŸā§āϝ āĻāĻŦāĻ‚ āĻĒāĻĻā§āϧāϤāĻŋāϗ⧁āϞāĻŋ āωāĻ¤ā§āϤāϰāĻžāϧāĻŋāĻ•āĻžāϰ āϏ⧂āĻ¤ā§āϰ⧇ āĻĒā§āϰāĻžāĻĒā§āϤāĨ¤
āĻāϟāĻŋ āĻĒā§āϰāϏāĻžāϰāĻŋāϤ āĻ•ā§āϞāĻžāϏ⧇āϰ āĻ…āĻ­āĻŋāĻ­āĻžāĻŦāĻ• āĻšāĻŋāϏāĻžāĻŦ⧇ āĻ•āĻžāϜ āĻ•āϰ⧇āĨ¤
It can't overwrite methods from a parent class.