promises examples.js

function one (x) {
  console.log(x);
}

function two (x, cb) {
  setTimeout(function () {
    console.log(x);
    cb(x);
  }, 1000);
}

function three (x) {
  return new Promise((resolve, reject) => {
    setTimeout(function () {
      resolve(x);
    }, 1000);
  });
}

function four (x) {
  return new Promise((resolve, reject) => {
    if (x > 5) {
      resolve(x);
    } else {
      reject(x);
    }
  });
}

function five (x) {
  return Promise.resolve(x);
}

function six (x) {
  return Promise.reject(x);
}

function seven (x) {
  return five(x).then(console.log);
}

function eight (x) {
  return six(x)
    .then(
      console.log,
      error => console.log('error', error)
    );
}

function nine (x) {
  return five(x)
    .then(
      () => { throw new Error('error')},
      error => console.log('error', error)
    );
}

function ten (x) {
  return five(x)
    .then(() => { throw new Error('error')})
    .catch(error => console.log('error', error));
}

function eleven (x) {
  console.log(x);
  return new Promise((resolve, reject) => {
    resolve(x);
  });
}

function twelve (x) {
  console.log(x);
  return new Promise((resolve, reject) => {
    if (x >= 2) {
      console.log('larger')
    } else {
      console.log('smaller');
    }
    resolve(x);
  });
}

function thirteen (x) {
  return Promise
    .all([twelve(1), twelve(2)])
    .then(console.log);
}

function fourteen (x) {
  twelve(1).then(console.log);
  twelve(3).then(console.log);
}

function fifteen (x) {
  return Promise.resolve(
    Promise.resolve(
      Promise.resolve(
        Promise.resolve(1)
      )
    )
  ).then(console.log);
}

function sixteen (x) {
  Promise
    .resolve(1)
    .then(x => { console.log(x); return x + 1; })
    .then(x => { console.log(x); throw x + 1; })
    .catch(x => { console.log(x); return x + 1; })
    .then(x => { console.log(x); return Promise.resolve(x + 1); })
    .then(x => { console.log(x); return Promise.reject(x + 1); })
    .catch(x => { console.log(x); })
}

async function seventeen (x) {
  return await Promise.resolve(1);
}

async function eighteen (x) {
  return await Promise.reject(1);
}

async function nineteen (x) {
  try {
    throw 1;
  } catch (e) {
    return 2;
  }
}

async function twenty (x) {
  try {
    throw 1;
  } catch (e) {
    throw 2;
  }
}

async function twentyone (x) {
  try {
    const response = await fetch('http://google.com');
    const html = response.text();
    return html;
  } catch (e) {
    return e;
  }
}

async function twentytwo (x) {
  return await twentyone().then(x => x.slice(0, 15)).then(console.log);
}

function twentythree (x) {
  let b = 0;
  return new Promise((resolve, reject) => {
    resolve(b++);
  });
}

function twentyfour () {
  const x = twentythree();
  x.then(console.log)
  x.then(console.log)
}