Posted by Kosal
Arrays and objects in JavaScript is fundamental for managing and manipulating data. Here's an overview:
Arrays are ordered collections of values, allowing storage of multiple items under a single variable name. They are defined using square brackets []
.
// Creating an empty array
let myArray = []
// Initializing an array with values
let numbers = [1, 2, 3, 4, 5]
let mixedArray = [1, 'two', true, { key: 'value' }]
// Accessing elements
console.log(numbers[0]) // Output: 1
console.log(mixedArray[2]) // Output: true
// Modifying elements
numbers[2] = 10 // Changing the third element to 10
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 are collections of key-value pairs, and they're defined using curly braces {}
.
// Creating an empty object
let myObj = {}
// Initializing an object with properties
let user = {
name: 'Kosal',
age: 30,
isStudent: false,
}
// Accessing properties
console.log(user.name) // Output: Kosal
console.log(user['age']) // Output: 30
// Modifying properties
user.age = 35 // Changing the age to 35
user['isStudent'] = true // Changing isStudent to true
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.You can have arrays that contain objects, creating more complex data structures.
let users = [
{ name: 'Sakni', age: 25 },
{ name: 'Bora', age: 30 },
{ name: 'Kosal', age: 35 },
]
console.log(users[1].name) // Output: Bora
// Loop through the array and output the values.
for (let user of users) {
console.log(`Name: ${user.name}, Age: ${user.age}`)
}
Bora
Name: Sakni, Age: 25
Name: Bora, Age: 30
Name: Kosal, Age: 35
Understanding arrays and objects and how to manipulate them is crucial in JavaScript for storing and organizing data efficiently.