Lesson 6: Objects and Arrays in JavaScript

Objects and arrays are used to store collections of data in JavaScript. They provide powerful ways to manage and organize data in your programs.

Objects

1. Creating an Object

Objects are collections of key-value pairs. Each key is a string (or symbol), and each value can be of any type.

      const person = {
          name: "John",
          age: 30,
          greet: function() {
              console.log("Hello, my name is " + this.name);
          }
      };
          

Example of Object:

      const car = {
          brand: "Toyota",
          model: "Camry",
          year: 2021,
          start: function() {
              console.log("The car is starting.");
          }
      };
      
      car.start(); // Output: The car is starting.
      console.log(car.brand); // Output: Toyota
              

2. Accessing Object Properties

Object properties can be accessed using dot notation or bracket notation.

      console.log(person.name); // Dot notation
      console.log(person["age"]); // Bracket notation
          

Example of Accessing Properties:

      console.log(car["model"]); // Output: Camry
      console.log(car.year); // Output: 2021
              

3. Modifying Objects

Object properties can be modified directly using dot notation or bracket notation.

      person.age = 31; // Modify using dot notation
      person["name"] = "Jane"; // Modify using bracket notation
          

Example of Modifying Object:

      car.year = 2022;
      car["brand"] = "Honda";
      
      console.log(car.year); // Output: 2022
      console.log(car.brand); // Output: Honda
              

Arrays

1. Creating an Array

Arrays are ordered collections of values. Each value in an array is called an element and can be accessed using its index.

      const numbers = [1, 2, 3, 4, 5];
          

Example of Array:

      const fruits = ["Apple", "Banana", "Cherry"];
      
      console.log(fruits[1]); // Output: Banana
              

2. Array Methods

JavaScript arrays come with various built-in methods to manipulate and interact with the array elements.

      fruits.push("Orange"); // Add an element to the end of the array
      fruits.pop(); // Remove the last element of the array
      fruits.shift(); // Remove the first element of the array
      fruits.unshift("Strawberry"); // Add an element to the beginning of the array
          

Example of Array Methods:

      fruits.push("Mango");
      console.log(fruits); // Output: ["Strawberry", "Apple", "Banana", "Cherry", "Mango"]
      
      fruits.pop();
      console.log(fruits); // Output: ["Strawberry", "Apple", "Banana", "Cherry"]