JavaScript - Arrays and Objects

Arrays and Objects

Arrays and objects are two fundamental data structures in JavaScript that allow you to store and organize data in different ways.

Arrays:

An array is a collection of values, each identified by an index or a key. The elements in an array can be of any data type, including other arrays or objects.

Creating an Array:

let colors = ['red', 'green', 'blue'];
let numbers = [1, 2, 3, 4, 5];

Accessing Elements:

let firstColor = colors[0]; // Accessing the first element (red)
let secondNumber = numbers[1]; // Accessing the second element (2)

Modifying Elements:

colors[1] = 'yellow'; // Changing the second element to 'yellow'
numbers.push(6); // Adding a new element (6) to the end of the array

Array Methods:

Arrays have a variety of built-in methods for performing operations on the elements. Some common methods include push(), pop(), shift(), unshift(), splice(), slice(), and concat().

Objects:

An object is a collection of key-value pairs, where each key is a string (or a symbol in ES6) and each value can be of any data type, including other objects or arrays.

Creating an Object:

let person = {
  firstName: 'John',
  lastName: 'Doe',
  age: 30,
  isStudent: false,
  address: {
    street: '123 Main St',
    city: 'Anytown',
    state: 'CA'
  }
};

Accessing Properties:

let firstName = person.firstName; // Accessing the first name ('John')
let streetAddress = person.address.street; // Accessing the street address ('123 Main St')

Modifying Properties:

Example:

person.age = 31; // Changing the age to 31
person['isStudent'] = true; // Another way to change a property value

Adding New Properties:

person.email = 'john@example.com'; // Adding a new property 'email'

Arrays of Objects:

Arrays and objects can be combined to create complex data structures. For example, an array of objects allows you to store a list of items where each item is represented as an object.