const convertArbitraryBase = (stringInBaseOne, baseOneCharacters, baseTwoCharacters) => {
if ([stringInBaseOne, baseOneCharacters, baseTwoCharacters].map(arg => typeof arg).some(type => type !== 'string')) {
throw new TypeError('Only string arguments are allowed')
}
[baseOneCharacters, baseTwoCharacters].forEach(baseString => {
const charactersInBase = [...baseString]
if (charactersInBase.length !== new Set(charactersInBase).size) {
throw new TypeError('Duplicate characters in character set are not allowed')
}
})
const reversedStringOneChars = [...stringInBaseOne].reverse()
const stringOneBase = baseOneCharacters.length
let value = 0
let placeValue = 1
for (const digit of reversedStringOneChars) {
const digitNumber = baseOneCharacters.indexOf(digit)
if (digitNumber === -1) {
throw new TypeError(`Not a valid character: ${digit}`)
}
value += (digitNumber * placeValue)
placeValue *= stringOneBase
}
let stringInBaseTwo = ''
const stringTwoBase = baseTwoCharacters.length
while (value > 0) {
const remainder = value % stringTwoBase
stringInBaseTwo = baseTwoCharacters.charAt(remainder) + stringInBaseTwo
value /= stringTwoBase
}
const baseTwoZero = baseTwoCharacters.charAt(0)
return stringInBaseTwo.replace(new RegExp(`^${baseTwoZero}+`), '')
}
(() => {
console.log(convertArbitraryBase('98', '0123456789', '01234567'))
console.log(convertArbitraryBase('98', '0123456789', 'abcdefgh'))
console.log(convertArbitraryBase('129', '0123456789', '01234567'))
})()