Have I Been Pwned

const sha1 = async str => {
  const msgBuffer = new TextEncoder('utf-8').encode(str);
  const hashBuffer = await crypto.subtle.digest('SHA-1', msgBuffer);
  const hashArray = [...new Uint8Array(hashBuffer)];
  const paddedHex = hashArray.map(b => b.toString(16).padStart(2, '0'));
  return paddedHex.join('').toUpperCase();
};

const request = hash => {
    const prefix = hash.substring(0, 5);
    const url = 'https://api.pwnedpasswords.com/range/' + prefix;
    return {
        response: fetch(url).then(r => r.text()),
        hash: hash
    };
};

const search = o => {
    const suffix = o.hash.slice(5);
    return o.response.then(text => text.includes(suffix));
};

const hibp = pass => sha1(pass).then(request).then(search);