JS encode / decode base62

base62.js

// Source : https://lowrey.me/encoding-decoding-base-62-in-es6-javascript/

const base62 = {
  charset: '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'.split(''),
  encode: integer => {
    if (integer === 0) {
      return 0;
    }
    let s = [];
    while (integer > 0) {
      s = [base62.charset[integer % 62], ...s];
      integer = Math.floor(integer / 62);
    }
    return s.join('');
  },
  decode: chars => chars.split('').reverse()
    .reduce((prev, curr, i) => prev + (base62.charset.indexOf(curr) * (62 ** i)), 0)
};

// Usage
let sha512 = "1fe3e26d11b5984d794563d66e9c98862f499753c9edaea49bfcbd0bc27138b2c78b8375561d24ea591cac6da535094779eaa9d30c8df6298f73fc493139cc2f";
console.log(base62.encode(parseInt("0x"+sha512)));