A Comprehensive Guide to JavaScript - Part 3 - Objects

Objects

An object is a non-primitive data type. It is a collection of related data or functionality. These consists of several variables and functions which are called properties and methods of the object.
Example:

var Student = {name: "Prajwal", age: "20"}; // Student object with two properties

Almost everything in javascript is an object. All javascript values such as Booleans, Strings, Numbers, Maths, Dates, Regular Expressions, Array and Functions are all objects.

Creating an Object

• Using an object literal:

var Car = {company: "Lamborghini", name: "Aventador", year: "2020"};

• Using new keyword:

var Car = new Object();
Car.company = "Lamborghini";
Car.name = "Aventador";
Car.year = "2020";

Adding New Properties to an Object

• Dot notation

Car.color = "royal blue"

• Bracket notation

Car['color'] = "royal blue"

Deleting Properties from an Object

delete Car.color;

Adding a Method to an Object

Car.fullname = function() {
    return this.company + " " + this.name;
};

Built-In Constructors

• New Object object

var a = new Object();

• New String object

var a = new String();

• New Number object

var a = new Number();

• New Boolean object

var a = new Boolean();

• New Array object

var a = new Array();

• New Regular Expression object

var a = new RegExp();

• New Function object

var a = new Function();

• New Date object

var a = new Date();

Using this for Object References

The keyword this is used in javascript to refer to the properties of the current object.

var Car1 = {name: "Lamborghini"};
var Car2 = {name: "Ferrari"};
function display() {
    console.log("Car name is: ", this.name);
}
Car1.display = display;
Car2.display = display;
Car1.display(); // Lamborghini
Car2.display(); // Ferrari

Objects play a very important role in javascript and I hope you've understood them well by now.

Thank You!