A constructor function in JavaScript is a special function used to create and initialize objects. It's like a blueprint for creating multiple similar objects. When you use the new keyword with a constructor function, it creates a new object based on that blueprint.
Example
- Define the constructor function
function Pet(name, type) { this.name = name; this.type = type; } - Create new pet objects
let pet1 = new Pet("Fluffy", "Cat"); let pet2 = new Pet("Buddy", "Dog"); console.log(pet1.name); // Output: Fluffy console.log(pet1.type); // Output: Cat console.log(pet2.name); // Output: Buddy console.log(pet2.type); // Output: Dog - Adding methods to constructor functions
function Pet(name, type) { this.name = name; this.type = type; this.describe = function() { return `${this.name} is a ${this.type}.`; }; } let pet1 = new Pet("Fluffy", "Cat"); let pet2 = new Pet("Buddy", "Dog"); console.log(pet1.describe()); // Output: Fluffy is a Cat. console.log(pet2.describe()); // Output: Buddy is a Dog. Extra sample
// Define the object function Phone (name, color, memory, price) { this.name = name, this.color = color, this.price = price, this.memory = memory, this.tellAbout = function() { return `${this.name} has ${this.memory}GB, and its color is ${this.color}.` } } // Create the object const iPhone_13 = new Phone('iPhone 13', 'blue', 256, 7000000); console.log(iPhone_13.tellAbout()); // iPhone 13 has 256GB, and its color is blue. 
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