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Cover image for A Comprehensive Guide to JavaScript - Part 3 - Objects

A Comprehensive Guide to JavaScript - Part 3 - Objects

K G Prajwal
Full-Stack Development and Data Engineering Enthusiast
・2 min read

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
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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"};
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  • Using new keyword:
var Car = new Object();
Car.company = "Lamborghini";
Car.name = "Aventador";
Car.year = "2020";
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Adding New Properties to an Object

  • Dot notation
Car.color = "royal blue"
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  • Bracket notation
Car['color'] = "royal blue"
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Deleting Properties from an Object

delete Car.color;
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Adding a Method to an Object

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

  • New Object object
var a = new Object();
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  • New String object
var a = new String();
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  • New Number object
var a = new Number();
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  • New Boolean object
var a = new Boolean();
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  • New Array object
var a = new Array();
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  • New Regular Expression object
var a = new RegExp();
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  • New Function object
var a = new Function();
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  • New Date object
var a = new Date();
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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
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Objects play a very important role in javascript and I hope you've understood them well by now.

Thank You!

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