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12+ JavaScript Array Methods : You need to know

12+ JavaScript Array Methods : You need to know

In this article we will learn about some basic array methods and their uses.

 ForEach

Loops over every element in an array and executes a callback function.

const arr = [1, 2, 3];

arr.forEach(num => console.log(num));

// 1, 2, 3

Map

Loops over each element in an array and executes a callback function and creates a new array with the return values of the callback function.

const arr = [1, 2, 3, 4, 5];

const arrMulti= arr.map(num => num * 2);

// [2, 4, 6, 8, 10]

Filter

Loops over each array elements and returns element which fulfill the condition.

const arr = [1, 2, 3, 4, 5];

const result= arr.filter(num => num > 2);

// [3, 4, 5]

Find

Finds the first element in the array that match a condition. 

const arr = [1, 2, 3, 4, 5];

const result= arr.find(num => num === 3);

// 3

FindIndex

Same as the find method, it returns the index of the first element that fulfils a specifc condition.

If none are found, -1 is returned.

const arr = [1, 2, 3, 4, 5];

const result= arr.findIndex(num => num === 3);

// 2

 Every

This method takes a callback that returns a boolean value. Every() will return true if the condition is valid for ALL the elements in the array.

const arr = [1, 2, 3, 4, 5];

const result= arr.every(num => num > 2);

// False

slice()

The slice() method Will return new array but only with the extracted parts

For example:

let arr = ['a', 'b', 'c', 'd', 'e'];

arr.slice(2) // ['c'.'d','e']

arr.slice(2, 4) // ["c", "d"]

arr.slice(-2) // ["d", "e"]

arr.slice(1, -2) // ["b", "c"]   

splice()

The splice() method works the same as slice but difference is it does actually change the original array and Extracted elemented will gone from origianl array.

Basically we use it to just delete one or more eleemnet frpm an array using splice

arr.splice(2);
arr // ["a", "b"]

Remove last element using splice() method:

arr.splice(-1)
arr//["a","b","c","d","e"]

Reverse()

The reverse method is used to reverse array element.

const arr2 = ['j', 'i', 'h', 'g', 'f'];

console.log(arr2.reverse());
console.log(arr2);

concat()

const letters = arr.concat(arr2);
console.log(letters);
console.log([...arr, ...arr2]);

join()

console.log(letters.join(' - '));

Conclusion:

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