30-seconds-of-code/snippets/insertAt.md

title, tags, expertise, author, cover, firstSeen, lastUpdated

title	tags	expertise	author	cover	firstSeen	lastUpdated
Insert value at array index	array	intermediate	chalarangelo	blog_images/messy-papers.jpg	2020-05-22T09:07:35+03:00	2020-10-20T23:02:01+03:00

Mutates the original array to insert the given values after the specified index.

• Use Array.prototype.splice() with an appropriate index and a delete count of 0, spreading the given values to be inserted.

const insertAt = (arr, i, ...v) => {
  arr.splice(i + 1, 0, ...v);
  return arr;
};

let myArray = [1, 2, 3, 4];
insertAt(myArray, 2, 5); // myArray = [1, 2, 3, 5, 4]

let otherArray = [2, 10];
insertAt(otherArray, 0, 4, 6, 8); // otherArray = [2, 4, 6, 8, 10]