How to Insert an Item into an Array at a Specific Index in JavaScript

Use the JavaScript splice() Method

You can use the splice() method to insert a value or an item into an array at a specific index in JavaScript. This is a very powerful and versatile method for performing array manipulations.

The splice() method has the syntax like array.splice(startIndex, deleteCount, item1, item2,...). To add elements to an array using this method, set the deleteCount to 0, and specify at least one new element, as demonstrated in the following example:

<script>
    var persons = ["Harry", "Clark", "John"];
    
    // Insert an item at 1st index position
    persons.splice(1, 0, "Alice");
    console.log(persons); // Prints: ["Harry", "Alice", "Clark", "John"]
    
    // Insert multiple elements at 3rd index position
    persons.splice(3, 0, "Ethan", "Peter");
    console.log(persons); // Prints: ["Harry", "Alice", "Clark", "Ethan", "Peter", "John"]
</script>