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Adding Items in a JavaScript Array

Adding Items in a JavaScript Array

Adding Items at Start, Middle, and End of a JavaScript

Md. Musfiqur Rahaman's photo
Md. Musfiqur Rahaman
·Sep 27, 2022·

3 min read

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Table of contents

  • Declaring an empty Array
  • Initializing an Array
  • Adding items at the beginning/start
  • Adding items in the middle
  • Adding elements at the end of the array
  • All at once

The array is one of the essential Data Structures. In JavaScript, we have many built-in Array methods to manipulate an array. In this article, we will learn how we can add items at the start, middle, and end of a JavaScript Array.

Declaring an empty Array

// We can declare an array using Array() constructor function
const arr = new Array();
// or Simply using an empty square bracket
const arr = [];

Initializing an Array

//  Initializing the array with two integers 3, 4
const arr = new Array(3, 4);
// or
const arr = [3, 4];

Now let's add items to this array.

Adding items at the beginning/start

  • We will use the unshift() method for doing this
  • You can add any number of items
  • You can add not only numbers but also different types of elements other than numbers
arr.unshift(1, 2)
// [1, 2, 3, 4]

Adding items in the middle

  • It is slightly tricky😉 but not much complex
  • Our current Array, const arr = [1, 2, 3, 4];
  • We want to add 7 and 8 in between 2 and 3
  • We will use the splice() function for this
  • splice() function takes 3 parameters
  • First Parameter: Before which position do we want to add
  • Second Parameter: How many numbers do we want to delete (We will not use this parameter as we don't want to delete any number now)
  • Third Parameter: The items we want to add in the middle
  • So, we will keep our second parameter as 0
  • After that, we will add the elements we want to add in the middle
  • splice(2, 0, 7, 8)
  • Before 3, the index of 3 is 2
  • 0 as Second Parameter as we don't want to do any delete operation
  • We want to add 7, 8 that's why we adding 7, 8 as the last parameter
  • You can add as many items as you want
  • You can add not only numbers but also different types of elements other than numbers
arr.splice(2, 0, 7, 8);
// Now, the new resultant array will be
// [1, 2, 7, 8, 3, 4]

Adding elements at the end of the array

  • This one is simple
  • We will use push() operation
  • You can add any number of items
  • You can add not only numbers but also different types of elements other than numbers
arr.push(5, 6);
// Now, the new resultant array will be
// [1, 2, 7, 8, 3, 4, 5, 6]

All at once

Now let's summarize the article with a single code snippet.

// Declaring an array
const arr = [];
console.log(arr);
// []

# Intializing an array
arr = [3, 4];
console.log(arr);
// [3, 4];

// Adding items at the beginning/ start of the array
arr.unshift(1, 2)
console.log(arr);
// [1, 2, 3, 4]

// Adding items in the middle of the array
arr.splice(2, 0, 7, 8);
console.log(arr);
// [1, 2, 7, 8, 3, 4]

// Adding items at the end of the array
arr.push(5, 6);
console.log(arr);
// [1, 2, 7, 8, 3, 4, 5, 6]

Thank you so much for reading this. Hope to see you in another article. This is my first published article. Please give me a like for the inspiration.

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