number to text

num = 271021678

function encode(n, arr = []) {
    if(n > 0) {
        d = n % 10
        return encode((n - d)/10, [d].concat(arr))
    } else {
        return arr.map(i => String.fromCharCode(i + 100)).join('')
    }
}

encoded = encode(num)
console.log(encoded)

function decode(text) {
    return parseInt(text.toLowerCase().split('').map(c => c.charCodeAt(0) - 100).join(''))
}

console.log(decode(encoded))