In JavaScript, constructor functions are used to create objects of the same type. They are a way of defining a blueprint for an object and then creating instances of that object.

Constructor functions are defined using the function keyword and are typically named with a capitalized first letter to distinguish them from regular functions.

The code showing the working of the Constructor Function is mentioned below -

function Person(name, age) { this.name = name; this.age = age; this.greet = function() { console.log(Hello, my name is ${this.name} and I am ${this.age} years old.); } } const person1 = new Person('Alice', 25); console.log(person1)
//Output: Person {name: 'Alice', age: 25, greet: ƒ}

Sub-topics related to Constructor Function

Some Sub-topics related to Constructor Function are mentioned below -

1. Prototypes - JavaScript uses prototypal inheritance, which means that objects can inherit properties and methods from other objects. This sub-topic covers how to use the prototype property to add methods and properties to objects and how to use inheritance in JavaScript.


2. new Keyword - The new keyword is used to create a new instance of an object. This sub-topic covers how to use new to create new objects from constructor functions. The code showing the working of the new keyword is mentioned below -
   
   

   // Constructor function for a person object function Person(name, age) { this.name = name; this.age = age; } // Creating a new instance of the person object using the new keyword const person1 = new Person('John', 30); console.log(person1.name); // Output: John console.log(person1.age); // Output: 30

   
   
3. Constructor Chaining - Constructor functions can be chained together to create more complex objects. This sub-topic covers how to use constructor chaining to create objects that inherit from multiple parent objects.



// Parent object constructor function function Person(name, age) { this.name = name; this.age = age; }
// Child object constructor function function Employee(name, age, position) { Person.call(this, name, age); // Calling parent constructor function with call method this.position = position; }
// Creating a new instance of the Employee object const employee1 = new Employee('John', 30, 'Manager'); console.log(employee1.name); // Output: John console.log(employee1.age); // Output: 30 console.log(employee1.position); // Output: Manager