Javascript Array.prototype.with()

I just discovered the with() method which takes an index value and a value to insert at that index and returns a new array with the value inserted at the index.

const arr = [1, 2, 3, 4, 5];
const newArr = arr.with(2, 'a');
console.log(newArr); // [1, 2, 'a', 4, 5]

You could do this before with something like arr[2] = 'a' but that would modify the original array.

The with() method became widely supported in 2021.

Read more about the with() method and alternatives in Stefan Judis’ post.