JavaScript - insert array inside another array

In this article, we would like to show you how to insert an array inside another array at a specific position in JavaScript.

In this example, we use apply() to execute splice() method on array1 and modify it by adding another array on insertIndex position using concat().

xxxxxxxxxx

const array1 = [1, 2, 5, 6];

const array2 = [3, 4];

​

const insertIndex = 2;

​

array1.splice.apply(array1, [insertIndex, 0].concat(array2));

​

console.log(array1); // [ 1, 2, 3, 4, 5, 6 ]

In this example, we present an alternative solution that uses splice() method with spread syntax (...).

xxxxxxxxxx

const array1 = [1, 2, 5, 6];

const array2 = [3, 4];

​

const insertIndex = 2;

​

array1.splice(insertIndex, 0, ...array2);

​

console.log(array1); // [ 1, 2, 3, 4, 5, 6 ]

1. Array.prototype.splice() - JavaScript | MDN
2. Function.prototype.apply() - JavaScript | MDN
3. Array.prototype.concat() - JavaScript | MDN