JavaScript Array

JavaScript arrays are versatile, allowing you to store and manipulate collections of objects more efficiently. Here is a comprehensive guide to understanding JavaScript programming, including creation, implementation, and common methods.

 

Creating Arrays

Array Literals

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

Array Constructor

let fruits = new Array("apple", "banana", "cherry");

 

Accessing Elements

You can access items/elements from array by its index number as given below,

let firstFruit = fruits[0]; // "apple"

The index number starts from 0 in the array.

Modifying Arrays

Adding Elements

• Using push() It adds the element at the end of the array.

fruits.push("date");
// fruits is now ["apple", "banana", "cherry", "date"]

• Using unshift() it adds the elements at the beginning of the array.

fruits.unshift("avocado");
// fruits is now ["avocado", "apple", "banana", "cherry", "date"]

 

Removing Elements

• Using pop() It removes the last element from the array.

let lastFruit = fruits.pop(); // lastFruit is "date"
// fruits is now ["avocado", "apple", "banana", "cherry"]

• Using shift() It removes the first element from the array.

let firstFruit = fruits.shift(); // firstFruit is "avocado"
// fruits is now ["apple", "banana", "cherry"]

 

Modifying Elements

• Using Index It updates the element at the given index number.

fruits[1] = "blueberry";
// fruits is now ["apple", "blueberry", "cherry"]

 

Common Array Methods

length Property- It returns the number of elements ih the array.

let numberOfFruits = fruits.length;
// numberOfFruits is 3

concat() Method- It combines multiple arrays into a single array.

let moreFruits = ["date", "elderberry"];
let allFruits = fruits.concat(moreFruits);
// allFruits is ["apple", "blueberry", "cherry", "date", "elderberry"]

slice() Method- It extracts a section of the array and returns a new array

let someFruits = fruits.slice(1, 3);
// someFruits is ["blueberry", "cherry"]

indexOf()- Returns the first index of the specified element, or -1 if not found.

let index = fruits.indexOf("cherry");
// index is 2

includes()- It checks if the array contains the specified element.

let hasApple = fruits.includes("apple");
// hasApple is true

forEach()- It iterates over each element.

fruits.forEach(fruit => console.log(fruit));
// Logs "apple", "blackberry", "cherry"

filter()- It returns a new array with the elements that satisfy the specific condition.

let longFruits = fruits.filter(fruit => fruit.length > 5);
// longFruits is ["blackberry"]

sort()- It arranges the table elements in a specific order.

let sortedFruits = fruits.sort();
// sortedFruits is ["apple", "blackberry", "cherry"]

 

Multidimensional Arrays

Create and Access Elements

syntax- 

let matrix = [
   [1, 2, 3],
   [4, 5, 6],
   [7, 8, 9]
];

Accessing elements-

let element = matrix[1][2]; // 6

 

Spread Operator

Copying and Concatenating Arrays

let newArray = [...array];
let combinedArray = [...array1, ...array2];

Example- 

let fruitsCopy = [...fruits];
let moreFruits = ["date", "elderberry"];
let allFruits = [...fruits, ...moreFruits];
// allFruits is ["apple", "blackberry", "cherry", "date", "elderberry"]

 

Once you understand and use these array features and methods, you can effectively manage and manipulate data collected in JavaScript.

 

Also, Read: Handling JavaScript Asynchronous Operations with Promises and Async/Await