TypeScript - insert element to array

In TypeScript it is not intuitive at first time how to insert element to array into some index position. Insert element into some index position operation can be achieved with Array.prototype.splice method. This article is focused on how to do it.

1. Insert element into the index position with Array.prototype.splice method example

//           index:       0    1    2    3
const array: string[] = ['a', 'b', 'c', 'd'];

// inserting 'new item' element into 1st index position
array.splice(1, 0, 'new item');

console.log(array);

Output:

[ 'a', 'new item', 'b', 'c', 'd' ]

Notes about Array.prototype.splice method:

• takes as first argument index into 1st index position
• takes as second argument number of removed elements - in this case we do not remove elements
• takes as third argument added element