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JavaScript in Detail: From Beginner to Advanced

JavaScript Constructor Functions

Explore how JavaScript constructor functions serve as blueprints for creating custom objects with properties and methods. Understand object creation with the new keyword, use of 'this' keyword, and how prototype objects enable shared behaviors among instances. Gain foundational knowledge for effective object-oriented programming in JavaScript.

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Background

We know what OOPs are and their class-based and/or prototype-based approach. The challenge when using OOPs is creating a general mechanism to generate custom objects. In this lesson, we will use functions to construct objects, also called constructor functions. This is the best approach to implement prototype-based OOPs.

Constructor functions

Constructor functions, or object constructor functions, contain blueprints to a type of object that has properties and methods to generate objects. All objects created from a constructor function will have the same properties and methods but not necessarily the same values.

Syntax

Let’s look at the syntax of a constructor function.

Node.js
function FunctionName(parameter1, parameter2,...){
    //all the properties of the object are initialized here
    //functions to be provided by objects are defined here
}

As we can see from above:

  • The keyword function defines the function.

  • The constructor function name should be capitalized, as per convention, just like FunctionName in the ...