How to push value in array as a particular index?

In JavaScript, you can use the splice() method to insert an element into an array at a specified index. The splice() method modifies the original array and adds or removes elements from it.

Here is an example of how you can use the splice() method to insert a value at a specific index in an array:

let arr = [1, 2, 3, 4, 5];
let index = 3;
let value = 6;

arr.splice(index, 0, value);

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

In the above example, the splice() method is called on the arr array with the following arguments:

• index: the index at which to insert the new value
• 0: the number of elements to be removed
• value: the value to be inserted at the specified index

Note that if you want to replace an existing value in the array, you can specify the number of elements to remove (greater than 0) before inserting the new value.