intToRoman.js

var intToRoman = function (num) {
    let output = "";
    const bases = [1000, 100, 10, 1];
    for (let base of bases) {
        const q = Math.floor(num / base);
        const rem = num % base
        if (q > 0) {
            output += toFullBaseRoman(q, base);
        }
        num = rem;
    }
    return output;
};

function toFullBaseRoman(num, base) {
    if (num === 0) {
        return "";
    }
    if (num < 4) {
        return repeatChar(baseMap[base], num);
    } else if (num === 4) {
        return `${baseMap[base]}${baseMap[5 * base]}`
    } else if (num === 5) {
        return baseMap[num * base];
    } else if (num > 5 && num < 9) {
        return `${baseMap[5 * base]}${repeatChar(baseMap[base], num - 5)}`
    } else {
        return `${baseMap[base]}${baseMap[base * 10]}`
    }

}

const baseMap = {
    1000: "M",
    500: "D",
    100: "C",
    50: "L",
    10: "X",
    5: "V",
    1: "I"
}

function repeatChar(char, times) {
    let str = "";
    for (let i = 0; i < times; i++) {
        str += char;
    }
    return str;
}