Javascript | Creating and using classes

JavaScript is a powerful object-oriented language, and creating and using classes is an important aspect of object-oriented programming. In this article, we’ll discuss the basics of creating and using classes in JavaScript, including how to define a class, create an object from a class, and use the properties and methods of an object.

Defining a Class

To define a class in JavaScript, we use the class keyword. The class can have a constructor function, properties, and methods.

Here’s an example of a simple Person class with a constructor function and two properties:

class Person {
  constructor(name, age) {
    this.name = name;
    this.age = age;
  }
}

In this example, the Person class has a constructor function that takes two arguments, name and age. The constructor function sets the name and age properties of the Person object.

Creating an Object from a Class

Once you’ve defined a class, you can create an object from it using the new keyword. Here’s an example of creating a Person object:

const person = new Person('John', 30);

In this example, we’ve created a Person object with the name 'John' and age 30. The new keyword creates a new instance of the Person class, with its properties set to the values passed as arguments.

Using Properties and Methods of an Object

Once you’ve created an object from a class, you can access its properties and methods using the dot notation. Here’s an example of accessing the name property of a Person object:

console.log(person.name); // Output: 'John'

In this example, we’re accessing the name property of the person object using the dot notation. We can also call methods of the Person class using the same notation. Here’s an example of calling a sayHello method of a Person object:

class Person {
  constructor(name, age) {
    this.name = name;
    this.age = age;
  }

  sayHello() {
    console.log(`Hello, my name is ${this.name}`);
  }
}

const person = new Person('John', 30);
person.sayHello(); // Output: 'Hello, my name is John'

In this example, we’ve added a sayHello method to the Person class, which logs a message to the console with the name property of the Person object.

Conclusion

Creating and using classes is an essential aspect of object-oriented programming in JavaScript. By defining a class, creating an object from it, and using its properties and methods, you can create powerful and flexible code that can be reused in a variety of contexts. With the examples and techniques outlined in this article, you’ll be well on your way to mastering the art of creating and using classes in JavaScript.