Working with Arrays and Objects in JavaScript

Arrays and objects in JavaScript is fundamental for managing and manipulating data. Here's an overview:

Arrays:

Arrays are ordered collections of values, allowing storage of multiple items under a single variable name. They are defined using square brackets [].

Creating Arrays:

1// Creating an empty array
2let myArray = []
3
4// Initializing an array with values
5let numbers = [1, 2, 3, 4, 5]
6let mixedArray = [1, 'two', true, { key: 'value' }]
7

Accessing and Modifying Array Elements:

1// Accessing elements
2console.log(numbers[0]) // Output: 1
3console.log(mixedArray[2]) // Output: true
4
5// Modifying elements
6numbers[2] = 10 // Changing the third element to 10
7

Useful Array Methods:

JavaScript provides numerous built-in methods to work with arrays:

• push(): Adds elements to the end of an array.
• pop(): Removes the last element from an array.
• shift(): Removes the first element from an array.
• unshift(): Adds elements to the beginning of an array.
• splice(): Adds or removes elements from a specific position in an array.

Objects:

Objects are collections of key-value pairs, and they're defined using curly braces {}.

Creating Objects:

1// Creating an empty object
2let myObj = {}
3
4// Initializing an object with properties
5let user = {
6  name: 'Kosal',
7  age: 30,
8  isStudent: false,
9}
10

Accessing and Modifying Object Properties:

1// Accessing properties
2console.log(user.name) // Output: Kosal
3console.log(user['age']) // Output: 30
4
5// Modifying properties
6user.age = 35 // Changing the age to 35
7user['isStudent'] = true // Changing isStudent to true
8

Useful Object Operations:

Objects have methods and operations to work with their properties:

• Object.keys(): Returns an array of an object's keys.
• Object.values(): Returns an array of an object's values.
• Object.entries(): Returns an array of an object's key-value pairs.

Arrays of Objects:

You can have arrays that contain objects, creating more complex data structures.

1let users = [
2  { name: 'Sakni', age: 25 },
3  { name: 'Bora', age: 30 },
4  { name: 'Kosal', age: 35 },
5]
6
7console.log(users[1].name) // Output: Bora
8
9// Loop through the array and output the values.
10for (let user of users) {
11  console.log(`Name: ${user.name}, Age: ${user.age}`)
12}
13

Output:

1Bora
2Name: Sakni, Age: 25
3Name: Bora, Age: 30
4Name: Kosal, Age: 35
5

Understanding arrays and objects and how to manipulate them is crucial in JavaScript for storing and organizing data efficiently.