function should replace in string A to B without case sensitive between A and B

replace_without_case_sensitive.js

function replace_without_case_sensitive (where, from, to) {
    return where.toLowerCase().split(from.toLowerCase()).reduce(
        (acc, _) =>
            [
                acc[0] + _.length + from.length,
                acc[1].concat(where.substring(acc[0], acc[0] + _.length))
            ],
        [0, []]
    )[1].join(to)
}