async

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/* Notes:
2	1. written like synchronous code
3    2. compatible with try/catch blocks
4    3. avoids chaining .then statements
5    4. async functions always return a promise
6    5. function pauses on each await expression
7    6. A non promise value is converted to 
8       Promise.resolve(value) and then resolved
9*/
10
11// Syntax
12// Function Declaration
13async function myFunction(){
14  await ... // some code goes here
15}
16  
17// Arrow Declaration
18const myFunction2 = async () => {
19  await ... // some code goes here
20}
21  
22 // OBJECT METHODS
23
24const obj = {
25	async getName() {
26		return fetch('https://www.example.com');
27	}
28}
29
30// IN A CLASS
31
32class Obj {
33	// getters and setter CANNOT be async
34	async getResource {
35		return fetch('https://www.example.com');
36	}
37}
38  

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}
11
12f();

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