JavaScript array splicing method

In JavaScript, you can use concat()methods to combine two or more arrays into one array. This method returns a new array containing the merged array elements. For example:

const arr1 = [1, 2, 3];
const arr2 = [4, 5, 6];
const arr3 = arr1.concat(arr2);
console.log(arr3); // [1, 2, 3, 4, 5, 6]

Alternatively, ...two or more arrays can be joined using the spread operator. For example:

const arr1 = [1, 2, 3];
const arr2 = [4, 5, 6];
const arr3 = [...arr1, ...arr2];
console.log(arr3); // [1, 2, 3, 4, 5, 6]

It should be noted that both methods return a new array, and the original array will not be modified. If you want to modify the original array, you can use push()the or splice()method to add new elements.