insertAtOrElse

insertAtOrElse(array, index, value, callback)

Inserts value at the specified index in array, returning a new array with the inserted element, or the result of calling callback with the array if the index is out of bounds.

data-first

insertAtOrElse([1, 2, 3], 10, 99, (arr) => arr.length); // 3

data-last

pipe(
    [1, 2, 3],
    insertAtOrElse(10, 99, (arr) => arr.length),
); // 3