Use Array.map()
to map values between start
(inclusive) and end
(exclusive) to value
.
Omit start
to start at the first element and/or end
to finish at the last.
const fillArray = (arr, value, start = 0, end = arr.length) =>
arr.map((v, i) => i >= start && i < end ? value : v);
// fillArray([1,2,3,4],'8',1,3) -> [1,'8','8',4]