roman.js

'use strict';

function toromans(number) {
    const decimals = [1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1];
    const romans = ["M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I"];
    let result = '';
    for (var i = 0; i <= decimals.length; i++) {
        const decimal = decimals[i];
        const roman = romans[i];
        const remain = number % decimal;
        while (remain < number) {
            number -= decimal;
            result += roman;
        }
    }
    return result;
}

console.log(toromans(9));