Day 18: Working with Arrays and Objects

Arrays

An array is a collection of items stored at contiguous memory locations. In JavaScript, arrays are used to store multiple values in a single variable. They can hold any type of data, including numbers, strings, and even other arrays.

Creating an Array

You can create an array using square brackets []:

let fruits = ['apple', 'banana', 'cherry'];

Accessing Array Elements

You can access elements in an array using their index (starting from 0):

console.log(fruits[0]); // Output: apple
console.log(fruits[1]); // Output: banana

Array Methods

Some common methods to manipulate arrays include:

• push(): Adds an item to the end of the array.
• pop(): Removes the last item from the array.
• shift(): Removes the first item from the array.
• unshift(): Adds an item to the beginning of the array.

fruits.push('orange'); // Adds 'orange' to the end
console.log(fruits); // Output: ['apple', 'banana', 'cherry', 'orange']

Objects

An object is a collection of key-value pairs. It is used to store data in a structured way. Each key is a string (or Symbol) and the value can be of any data type.

Creating an Object

You can create an object using curly braces {}:

let person = {
    name: 'John',
    age: 30,
    job: 'developer'
};

Accessing Object Properties

You can access properties using dot notation or bracket notation:

console.log(person.name); // Output: John
console.log(person['age']); // Output: 30

Object Methods

You can also define functions as methods within an object:

person.greet = function() {
    console.log('Hello, my name is ' + this.name);
};

person.greet(); // Output: Hello, my name is John

Summary

• Arrays are used for ordered collections of items.
• Objects are used for storing data in key-value pairs.

Assignment 18

1. Create an array called colors with at least five different color names as strings.
2. Write a function called addColor that takes a color as an argument and adds it to the colors array.
3. Create an object called car that includes properties: make, model, and year. Also, add a method called describe that logs a description of the car.
4. Finally, call the describe method on the car object.