JavaScript - insert item into array at specific index

In this article, we would like to show you how to insert item into array at specific index using JavaScript.

Quick solution:

// ONLINE-RUNNER:browser;

var array = ['a', 'b', 'd'];
var index = 2;
var item = 'c';

array.splice(index, 0, item); // insert item at index (removing 0 items)

console.log(array); // [ 'a', 'b', 'c', 'd' ]

Note:

The second argument - 0 is the number of items to delete while inserting the item.

Practical example

In this example, we extend the Array object by adding custom insert() method that accepts 2 arguments: index at which we want to insert the item, and the item.

// ONLINE-RUNNER:browser;

Array.prototype.insert = function(index, item) {
  this.splice(index, 0, item);
};

var array = ['a', 'b', 'd'];

array.insert(2, 'c');

console.log(array); // [ 'a', 'b', 'c', 'd' ]

References

1. Array.prototype.splice() - JavaScript | MDN