function withDefaults(value, array) {
  for (let i =0; i < array.length; i += 1) {
    if (!array[i]) {
      array[i] = value;
    }
  }
  return array;
}

withDefaults(14, [1,2,3,4]);
withDefaults(14, [42,null,null,9]);
withDefaults(14, [0, 5, null]);

function titleize(str) {
  let words = str.split(" ");
  return words
    .map(word => `${word[0].toUpperCase()}${word.slice(1)}`)
    .join(" ");
}

titleize("why elm?") // Why Elm?

function request(url, { headers }) {
    return Promise(...);
}

/**
 * Create a secure password hash from a password string.
 *
 * @param {string} password - The password to hash
 * @param {Object} [opts] - See below
 * @param {string} [opts.salt] - The salt used to create the hash
 * @param {number} [opts.keylen=256] - Length of the underlying hashing key
 * @param {string} [opts.digest='sha256'] - The digest algorithm to use
 * @returns {Password} An opaque representation of a password and its 
 *   corresponding hexadecimal digest.
 */
static hash(password, opts = {}) {
  const salt = opts.salt || crypto.randomBytes(64).toString('hex');
  const iterations = opts.iterations || Config.passwords.iterations;
  const keylen = opts.keylen || 512;
  const digest = opts.digest || 'sha512';

  const hash = crypto
    .pbkdf2Sync(password, salt, iterations, keylen, digest)
    .toString('base64');

  return new Password({ hash, salt, iterations, keylen, digest });
}

function sum(values) {
  let total = 0;
  for (let i = 0; i <= values.length; i += 1) { total += values[i]; }
  return total;
}

sum([1,2,3,4,5]);

const re = new RegExp(/[a-f0-9]{7}/, 'g');

const commits = `
053eede Bump version to 4.0.1
15e4e82 Make token_type parsing case-insensitive
`

while(res = re.exec(commits)) {
  console.log(res[0]);
}
console.log(re.exec(commits)[0]);

const re = new RegExp(/[a-f0-9]{7}/, 'g');

const commits = `
053eede Bump version to 4.0.1
15e4e82 Make token_type parsing case-insensitive
`

console.log(re.exec(commits)[0]);
console.log(re.exec(commits)[0]);
console.log(re.exec(commits)[0]);

// 053eede
// 15e4e82
// TypeError: Cannot read property '0' of null

function getJSON(url) {
  return new Promise(resolve => {
    let req = new XMLHttpRequest()
    req.addEventListener("Load", () => resolve(JSON.parse(req.responseText)));
    req.open("GET", url);
    req.send();
  });
}

getJSON("https://swapi.co/api/people/1").then(res => ...);
getJSON("https://swapi.co:1337/api/people/1").then(res => ...);
getJSON("https://swapi.co/api/patate/1").then(res => ...);

npm i react-dom@latest --please-dont-break-my-app-(too-much)