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
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We will use the
splice()function for this -
splice()function takes 3 parameters -
First Parameter: Before which position do we want to add
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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)
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Third Parameter: The items we want to add in the middle
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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
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0 as Second Parameter as we don't want to do any delete operation
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We want to add 7, 8 that's why we adding 7, 8 as the last parameter
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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.
COPY
// 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]
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