How to prepend a value to the beginning of a JS array

To add a new value to the beginning of the JS array, you can use the function Array.unshift. Here’s how it works.

const arr = [1, 2, 3];

arr.unshift(0);

console.log(arr); // [ 0, 1, 2, 3 ]

Array.unshift works with multiple arguments.

const arr = [1, 2, 3];

arr.unshift(-2, -1, 0);

console.log(arr); // [ -2, -1, 0, 1, 2, 3 ]

Alternatively, you can append new values to the end of the JavaScript array using the function Array.push.