Objects in JavaScript

An object is a collection of properties (key and value). It is the foundation of almost everything in JavaScript.

Create and Access

const persona = {
    nombre: "Juan",
    edad: 30,
    saludar: function() {
        console.log("Hello!");
    }
};

// Dot notation (Standard)
console.log(persona.nombre);

// Bracket notation (For dynamic names or with spaces)
console.log(persona["edad"]);

Manipulation

  • Add: persona.trabajo = "Dev";
  • Delete: delete persona.edad;
  • Check: "nombre" in persona; // true

The concept of this

The reserved word this refers to the current object in which the code is being executed. Its value changes depending on how the function is called.

const usuario = {
    nombre: "Facu",
    presentarse() {
        console.log(`Hi, I'm ${this.nombre}`);
    }
};

usuario.presentarse(); // "Hi, I'm Facu"

Inside an object method, this lets us access the other properties of that same object.