How to append an element in an array in JavaScript ?

In this article, we will see how to append an element in an array in JavaScript. There are several methods for adding new elements to a JavaScript array.

JavaScript push() Method: This method will add an element to the end of an array, while its twin function, the pop() method, will remove an element from the end of the array. If you need to add an element or multiple elements to the end of an array, the push() method will almost always be your simplest and quickest option. 

Syntax:

array.push(item1, item2, ..., itemX)

Parameters:

• item1, item2, …, itemX: These are required parameters. The item(s) to be added to the end of the array. 

Example: In this example, we will be adding new elements to the end of the array using the push() method.

javascript

let Geeks = ["Geeks1", "Geeks2", "Geeks3", "Geeks4"];

console.log("Original Array: " + Geeks);

Geeks.push("Geeks5", "Geeks6");

console.log("Updated Array: " + Geeks);

Output

Original Array: Geeks1,Geeks2,Geeks3,Geeks4
Updated Array: Geeks1,Geeks2,Geeks3,Geeks4,Geeks5,Geeks6

JavaScript unshift() Method: This method will add an element to the beginning of an array, while its twin function, shift(), will remove one element from the beginning of the array. 

Syntax: 

array.unshift(item1, item2, ..., itemX)

Parameter: 

• item1, item2, …, itemX: These are required parameters. The item(s) to be added to the beginning of the array. 

Example: In this example, we will be adding new elements to the beginning of the array using the unshift() method.

javascript

let Geeks = ["Geeks1", "Geeks2", "Geeks3", "Geeks4"];

console.log("Original Array: " + Geeks);

Geeks.unshift("Geeks5", "Geeks6");

console.log("Updated Array: " + Geeks);

Output

Original Array: Geeks1,Geeks2,Geeks3,Geeks4
Updated Array: Geeks5,Geeks6,Geeks1,Geeks2,Geeks3,Geeks4

JavaScript splice() Method: This method modifies the content of an array by removing existing elements and/or adding new elements. 

Syntax: 

array.splice(index, howmany, item1, ....., itemX)

Parameter: 

• index: This is a required parameter. An integer that specifies at what position to add/remove items, Use negative values to specify the position from the end of the array
• howmany: This is an Optional parameter. The number of items to be removed. If set to 0, no items will be removed.
• item1, item2, …, itemX: These are Optional parameters. The new item(s) are to be added to the array.

Example: In this example, we will be adding new elements at the 3rd index of the array using the splice() method.

Javascript

let Geeks = ["Geeks1", "Geeks2", "Geeks3", "Geeks4"];

console.log("Original Array: " + Geeks);

Geeks.splice(2, 1, "Geeks5", "Geeks6");

console.log("Updated Array: " + Geeks);

Output

Original Array: Geeks1,Geeks2,Geeks3,Geeks4
Updated Array: Geeks1,Geeks2,Geeks5,Geeks6,Geeks4

JavaScript concat() Method: This method returns a new combined array comprised of the array on which it is called, joined with the array (or arrays) from its argument. This method is used to join two or more arrays and this method does not change the existing arrays, but returns a new array, containing the values of the joined arrays. 

Syntax: 

array1.concat(array2, array3, ..., arrayX)

Parameter: 

• array2, array3, …, arrayX: These are required parameters. The arrays are to be joined.

Example: In this example, we will merge three arrays together using the concat() method of JavaScript.

Javascript

let g1 = ["Geeks1", "Geeks2"];
let g2 = ["Geeks3", "Geeks4"];
let g3 = ["GeeksForGeeks"];

let g4 = g1.concat(g2, g3);

console.log(g4);

Output

[ 'Geeks1', 'Geeks2', 'Geeks3', 'Geeks4', 'GeeksForGeeks' ]

Javascript spread operator: The Spread operator allows an iterable to expand in places where 0+ arguments are expected. It is mostly used in the variable array where there is more than 1 value is expected. It allows us the privilege to obtain a list of parameters from an array.

Syntax:

var variablename1 = [...value];

Example:

Javascript

let Array1 = [2, 4, 6, 8];
let Array2 = [3, 5, 7]

newArray = [ ...Array1, ...Array2]

console.log(newArray);

Output

[
  2, 4, 6, 8,
  3, 5, 7
]