Objects in JavaScript

What is it?

In JavaScript, the object data type is used to store key-value collections and complex data structures. It can be thought as an entity having state and behavior, which are implemented as properties and methods.

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Defining objects

To create an object, one can create it using the object literal, using the let or const keyword, or with an object constructor.

Using the Object literal

We can create objects using the { } literal. This is a fast way to create any object, but not as flexible as other options.

let myself = {
	name: "Lucas",
	favoriteBand: "Radiohead",
	Greet: function () {
		console.log(`Hi! I am ${myself.name}.`)
 
	}
};
 
myself.Greet(); // Prints "Hi! I am Lucas."

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Creating instances of Object

Using the Object keyword, one can create a object directly. This is not a so fast way of declaring objects.

let myself = new Object();
myself.name = "Lucas";
myself.favoriteBand = "Radiohead";
myself.Greet = function() {
	console.log(`Hi! I am ${myself.name}.`);
};
 
myself.Greet();

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Using a object constructor

Using a object constructor is a more concise way of creating objects, once it can be applied to multiple different instances without too much repeated code.

function CreatePerson(name, favoriteBand){
	this.name = name;
	this.favoriteBand = favoriteBand;
	this.Greet = function() {
		console.log(`Hi! I am ${this.name}.`);
	};
}
 
let me = new CreatePerson("Lucas", "Radiohead");
me.Greet();

However, one would be better using a class constructor, which would serve the same purpose, but more flexible.

class CreatePerson {
	constructor(name, favoriteBand) {
		this.name = name;
		this.favoriteBand = favoriteBand;
		this.Greet = function () {
			console.log(`Hi! I am ${this.name}.`);
		};
	}
}
 
let me = new CreatePerson("Lucas", "Radiohead");
me.Greet();