Async JS

asyncawait.js

const posts = [
  {
    id: 1,
    title: 'Post One',
    body: 'This is post one'
  },
  {
    id: 2,
    title: 'Post Two',
    body: 'This is post two'
  }
];

function getPosts() {
  setTimeout(() => {
    let output = '';
    posts.forEach((post, index) => {
      output += `<li>${post.title}</li>`;
    });
    document.body.innerHTML = output;
  }, 1000);
}

function createPost(post) {
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      posts.push(post);
      const error = true;

      if (!error) resolve();
      else reject('Something went wrong!');
    }, 2000);
  });
}

async function init() {
  try {
    await createPost({
      id: 3,
      title: 'Post Three',
      body: 'This is post three'
    });
    getPosts();
  } catch (err) {
    console.log(err);
  }
};

init();

callback.js

const posts = [
  {
    id: 1,
    title: 'Post One',
    body: 'This is post one'
  },
  {
    id: 2,
    title: 'Post Two',
    body: 'This is post two'
  }
];

function getPosts() {
  setTimeout(() => {
    let output = '';
    posts.forEach((post, index) => {
      output += `<li>${post.title}</li>`;
    });
    document.body.innerHTML = output;
  }, 1000);
}

function createPost(post, callback) {
  setTimeout(() => {
    posts.push(post);
    callback();
  }, 2000);
}

getPosts();
createPost({
  id: 3,
  title: 'Post Three',
  body: 'This is post three'
}, getPosts);

promise.js

const posts = [
  {
    id: 1,
    title: 'Post One',
    body: 'This is post one'
  },
  {
    id: 2,
    title: 'Post Two',
    body: 'This is post two'
  }
];

function getPosts() {
  setTimeout(() => {
    let output = '';
    posts.forEach((post, index) => {
      output += `<li>${post.title}</li>`;
    });
    document.body.innerHTML = output;
  }, 1000);
}

function createPost(post) {
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      posts.push(post);
      const error = true;

      if (!error) resolve();
      else reject('Something went wrong!');
    }, 2000);
  });
}

getPosts();
createPost({
    id: 3,
    title: 'Post Three',
    body: 'This is post three'
  })
  .then(getPosts)
  .catch(err => console.log(err));

// Promise.all([promise1, promise2, promise3]).then(vals => console.log(vals));