Class inheritance is a fundamental concept in object-oriented programming that allows a class to inherit properties and methods from another class. In JavaScript, class inheritance is implemented using the extends keyword.
Class inheritance allows a subclass to inherit properties and methods from a superclass. This means that the subclass can reuse code from the superclass, which can save time and effort in development. The subclass can also add its own properties and methods, or override those of the superclass.
Let's take a look at an example:
class Animal {
constructor(name) {
this.name = name;
}
speak() {
console.log(`${this.name} makes a noise.`);
}
}
class Dog extends Animal {
speak() {
console.log(`${this.name} barks.`);
}
}
let dog = new Dog('Rufus');
dog.speak(); // Output: "Rufus barks."
In this example, we have a superclass called Animal and a subclass called Dog. The Dog class extends the Animal class using the extends keyword. This means that the Dog class inherits the name property and speak() method from the Animal class.
The Dog class also overrides the speak() method of the Animal class with its own implementation. When we create a new instance of the Dog class and call the speak() method, it outputs "Rufus barks."
We can also call the speak() method of the Animal class on an instance of the Dog class:
let animal = new Animal('Generic Animal');
animal.speak(); // Output: "Generic Animal makes a noise."
dog.speak(); // Output: "Rufus barks."
In this example, we create a new instance of the Animal class and call its speak() method. It outputs "Generic Animal makes a noise." We then call the speak() method of the Dog class on the dog instance, which outputs "Rufus barks."
This demonstrates how class inheritance allows a subclass to inherit properties and methods from a superclass, and how the subclass can override or add its own properties and methods.
Class inheritance is a powerful concept in object-oriented programming that allows classes to reuse code from other classes. In JavaScript, class inheritance is implemented using the extends keyword. This allows a subclass to inherit properties and methods from a superclass, and to override or add its own properties and methods.