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Chapter XX · Classes

super

The `super` keyword is used to call constructor methods or access parent class properties and functions.

01 How It Works

Think of passing required base materials up to a master supervisor constructor template.

`super()` must be called in a child constructor before using the `this` keyword to ensure parent initialization completes.

example.js
class Parent {
  constructor(name) { this.name = name; }
}
class Child extends Parent {
  constructor(name, age) {
    super(name); // Calls parent constructor
    this.age = age;
  }
}

  1. 1. Extend a parent class.

  2. 2. Invoke `super(args)` inside the child constructor.

  3. 3. Access parent methods using `super.methodName()`.

02 Practical Example

Here is how you might see this concept applied in real-world code:

practical.js
class Vehicle {
  start() { console.log("Vehicle started"); }
}
class Car extends Vehicle {
  start() {
    super.start();
    console.log("Car engine running");
  }
}

Key Takeaway

`super` is essential for initializing parent states and invoking parent methods in subclassing.

Related Concepts