What is Constructor?

#javascript #webdev #beginners #tutorial

Constructor

A constructor is a special function/method used to initialize an object when it is created.

Function Constructor
A function constructor is a normal function used with the newkeyword to create and initialize objects.

Example

function Student(name, age) {
    this.name = name;
    this.age = age;
}

const s1 = new Student("Divya", 20);
const s2 = new Student("Aruna", 22);

console.log(s1.name); // Divya
console.log(s2.age);  // 22

Keywords Points

Function name usually starts with a capital letter
new keyword is mandatory
this refers to the new object

How it Works

const user = new Person("Divya", 22);

Creates an empty object {}
Sets this to that object
Assigns values (this.name, this.age)
Returns the object

Constructor in Class

A constructor is a method inside a class that:

Runs automatically when an object is created
Is used to set initial values (properties)

Example

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

const p1 = new Person("Divya", 22);

console.log(p1.name); // Divya
console.log(p1.age);  // 22