Array Methods

Array methods are built-in functions that allow various operations on arrays, such as adding, removing, or transforming elements. Here are some of the most commonly used array methods:

1. push()

Adds one or more elements to the end of an array and returns the new length of the array.

let fruits = ['Apple', 'Banana'];
let res=fruits.push('Cherry','Orange');

console.log('Fruits: '+fruits); 
console.log('Length of new array: '+res);

/*Output
    Fruits: Apple,Banana,Cherry,Orange
    Length of new array: 4
*/

2. pop()

Removes the last element from an array and returns that element.

let fruits = ['Apple', 'Banana','Cherry','Orange'];
let res=fruits.pop();

console.log('Fruits: '+fruits); 
console.log('Removed Fruits: '+res);

/*Output
    Fruits: Apple,Banana,Cherry
    Removed Fruits: Orange
*/

3. unshift()

Adds one or more elements to the beginning of an array and returns the new length of the array.

let fruits = ['Apple', 'Banana'];
let res=fruits.unshift('Cherry','Orange');

console.log('Fruits: '+fruits); 
console.log('Length of the new array: '+res);

/*Output
    Fruits: Cherry,Orange,Apple,Banana
    Length of the new array: 4
*/

4. shift()

 Removes the first element from an array and returns that element.

let fruits = ['Apple', 'Banana','Cherry','Orange'];
let res=fruits.shift();

console.log('Fruits: '+fruits); 
console.log('Removed Element: '+res);

/*Output
    Fruits: Banana,Cherry,Orange
    Removed Element: Apple
*/

---

5. sort()

The sort method is used to sort the elements of an array in place, meaning it changes the original array and returns the sorted array.

let arr = [3, 1, 4, 2];
arr.sort();
console.log(arr);
/*Output: 
    [ 1, 2, 3, 4 ]
*/

6. reverse()

The reverse method is used to reverse the order of elements in an array in place. This method modifies the original array and returns the reversed array.

let arr = [1, 2, 3,4];
arr.reverse();
console.log(arr);
/*Output: 
    [ 4, 3, 2, 1 ]
*/

7. concat()

The concat method is specifically designed to merge arrays. It returns a new array and does not modify the original arrays.

let arr1 = [1, 2, 3];
let arr2 = [4, 5, 6];
let mergedArr = arr1.concat(arr2);
console.log(mergedArr);

/*Output: 
    [ 1, 2, 3, 4, 5, 6 ]
*/

You can also concatenate more than two arrays at once.

let arr1 = [1, 2, 3];
let arr2 = [4, 5, 6];
let arr3 = [7, 8, 9];
let mergedArr = arr1.concat(arr2,arr3);
console.log(mergedArr);

/*Output: 
    [1, 2, 3, 4, 5,6, 7, 8, 9]
*/

8. Spread Operator (...)

The spread operator (...) is a more modern and concise way to merge arrays. It creates a new array by spreading the elements of existing arrays.

let arr1 = [1, 2, 3];
let arr2 = [4, 5, 6];
let mergedArr = [...arr1, ...arr2];
console.log(mergedArr);

/*Output: 
    [1, 2, 3, 4, 5, 6]
*/

This method also works for merging more than two arrays.

let arr1 = [1, 2, 3];
let arr2 = [4, 5, 6];
let arr3 = [7, 8, 9];
let mergedArr = [...arr1, ...arr2, ...arr3];
console.log(mergedArr);

/*Output: 
    [1, 2, 3, 4, 5, 6, 7, 8, 9]
*/

9. splice()

The splice method in JavaScript/Node is a powerful way to add, remove, and replace elements in an array. It changes the contents of an array by removing or replacing existing elements and/or adding new elements in place.

⮚ read more about the splice method

Syntax

array.splice(start, deleteCount, item1, item2, ...);

Examples

let arry=['a','b','c','d'];

let res=arry.splice(1,1,'x','y'); // starts at index 1, removes 1 element (b), add x, y

console.log(arry);  //array after adding x, y [ 'a', 'x', 'y', 'c', 'd' ]
console.log(res);  //removed element [b]

/*Output
    [ 'a', 'x', 'y', 'c', 'd' ]
    [ 'b' ]
*/

10. slice()

The slice method in JavaScript is used to extract a portion of an array into a new array without modifying the original array. The slice method returns a shallow copy of a portion of an array into a new array object selected from start to end (end not included). The original array will not be modified.

Syntax:

array.slice(start, end);

Example

let arr = ['a', 'b', 'c', 'd', 'e'];
let slicedArr = arr.slice(1, 3);      // Slices from index 1 to 3 (3 not included)
console.log(slicedArr);              // ['b', 'c']
console.log(arr);                   //  ['a', 'b', 'c', 'd', 'e'] (original array is not modified)

/*Output
    [ 'b', 'c' ]
    [ 'a', 'b', 'c', 'd', 'e' ]
*/

11. indexOf

Returns the first index at which a given element can be found in the array, or -1 if it is not present.

let arr = ['a', 'b', 'c', 'd', 'e'];
let indexOfC = arr.indexOf('c');
let indexOfG = arr.indexOf('g');
console.log(indexOfC);            //2
console.log(indexOfG);           // -1 (g not present in the array)

/*Output
    2
    -1
*/

12. includes

The includes method determines whether an element exists in an array or not. It returns true if the element is found, and false otherwise. It is case-sensitive. This means it will only find a string in the array if the case matches exactly.

let arr = ['apple', 'banana', 'Cherry'];
console.log(arr.includes('apple'));         // Output: true
console.log(arr.includes('Banana'));       // Output: false (case-sensitive)

/*Output
    true
    false
*/

These methods offer a comprehensive toolkit for manipulating arrays in JavaScript. Mastering these methods allows for the effective performance of a wide range of array operations, making it easier to handle various programming tasks efficiently.