javascript async await

1async function f() {
2
3  try {
4    let response = await fetch('/no-user-here');
5    let user = await response.json();
6  } catch(err) {
7    // catches errors both in fetch and response.json
8    alert(err);
9  }
10}

1// Old School Javascript Invoke
2(async function() {
3	await someAsyncFunction();
4})();
5
6//New ES6 Javascript Invoke
7(async () => {
8	await someAsyncFunction();
9})();

1const data = async ()  => {
2  const got = await fetch('https://jsonplaceholder.typicode.com/todos/1');
3  
4  console.log(await got.json())
5}
6
7data();

1async function showAvatar() {
2
3  // read our JSON
4  let response = await fetch('/article/promise-chaining/user.json');
5  let user = await response.json();
6
7  // read github user
8  let githubResponse = await fetch(`https://api.github.com/users/${user.name}`);
9  let githubUser = await githubResponse.json();
10
11  // show the avatar
12  let img = document.createElement('img');
13  img.src = githubUser.avatar_url;
14  img.className = "promise-avatar-example";
15  document.body.append(img);
16
17  // wait 3 seconds
18  await new Promise((resolve, reject) => setTimeout(resolve, 3000));
19
20  img.remove();
21
22  return githubUser;
23}
24
25showAvatar();

1function resolveAfter2Seconds() {
2  return new Promise(resolve => {
3    setTimeout(() => {
4      resolve('resolved');
5    }, 2000);
6  });
7}
8
9//async function:
10async function asyncCall() {
11  console.log('calling');
12  const result = await resolveAfter2Seconds();
13  console.log(result);
14  // expected output: 'resolved'
15}
16
17asyncCall();

1// The await operator in JavaScript can only be used from inside an async function.
2// If the parameter is a promise, execution of the async function will resume when the promise is resolved
3// (unless the promise is rejected, in which case an error will be thrown that can be handled with normal JavaScript exception handling).
4// If the parameter is not a promise, the parameter itself will be returned immediately.[13]
5
6// Many libraries provide promise objects that can also be used with await,
7// as long as they match the specification for native JavaScript promises.
8// However, promises from the jQuery library were not Promises/A+ compatible until jQuery 3.0.[14]
9
10async function createNewDoc() {
11  let response = await db.post({}); // post a new doc
12  return await db.get(response.id); // find by id
13}
14
15async function main() {
16  try {
17    let doc = await createNewDoc();
18    console.log(doc);
19  } catch (err) {
20    console.log(err);
21  }
22}
23main();
24