JavaScript Interview Question #108

What are constructor functions?

Closures, Prototypes, Classes & Advanced Functions Mid-Level Intermediate

Quick Interview Answer

A constructor function is an ordinary constructable function intended to create objects when called with new. By convention its name begins with a capital letter.

Detailed Explanation

A constructor function is an ordinary constructable function intended to create objects when called with new. By convention its name begins with a capital letter.

Instance-specific data is usually assigned to this inside the constructor, while shared methods can be placed on the constructor's prototype. ES6 class syntax provides a clearer syntax for many of the same prototype-based mechanics.

Code Example

function Employee(id, name) {
    this.id = id;
    this.name = name;
}

Employee.prototype.getDisplayName = function () {
    return `${this.id} - ${this.name}`;
};

const employee = new Employee(1, "Asif");