export function convertBase({ value, fromBase, toBase }: { value: string; fromBase: number; toBase: number }) { const range = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ+/'.split(''); const fromRange = range.slice(0, fromBase); const toRange = range.slice(0, toBase); let decValue = value .split('') .reverse() .reduce((carry: number, digit: string, index: number) => { if (!fromRange.includes(digit)) { throw new Error('Invalid digit `' + digit + '` for base ' + fromBase + '.'); } return (carry += fromRange.indexOf(digit) * Math.pow(fromBase, index)); }, 0); let newValue = ''; while (decValue > 0) { newValue = toRange[decValue % toBase] + newValue; decValue = (decValue - (decValue % toBase)) / toBase; } return newValue || '0'; }