understanding async await code example

Example 1: async await

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

data();

Example 2: js async await

/* Notes:
	1. written like synchronous code
    2. compatible with try/catch blocks
    3. avoids chaining .then statements
    4. async functions always return a promise
    5. function pauses on each await expression
    6. A non promise value is converted to 
       Promise.resolve(value) and then resolved
*/

// Syntax
// Function Declaration
async function myFunction(){
  await ... // some code goes here
}
  
// Arrow Declaration
const myFunction2 = async () => {
  await ... // some code goes here
}
  
 // OBJECT METHODS

const obj = {
	async getName() {
		return fetch('https://www.example.com');
	}
}

// IN A CLASS

class Obj {
	// getters and setter CANNOT be async
	async getResource {
		return fetch('https://www.example.com');
	}
}

Example 3: await async

function afterPrintSave() {
    Xrm.Page.data.save().then(
        function () {
            resolve();
        },
        function (err) {
            resolve(alert(err.message));
        }
    );
}

Example 4: async await

// ASYNC will always returns promises
// NOTE : AWAIT should be kept only inside ASYNC function
// AWAIT can't be used in regular function
/* TIPS : Js is single threaded & synchronous in nature BUT, we can
          make it as asyncronous by using (ASYNC/AWAIT)*/

//(Example 1 : fetching Random Image)
async function RandomImage(){  //remember async and await is powerful for async operations, always await should be inside of async only.

  try {
    const raw_response = await fetch("https://www.themealdb.com/api/json/v1/1/random.php");
      if (!raw_response.ok) { // check for the 404 errors
          throw new Error(raw_response.status);
      }
    const json_data = await raw_response.json();  //AWAIT
    let data = json_data.meals[0];

    console.log(data);
  }
  catch (error) { // catch block for network errors
      console.log(error); 
  }
}
RandomImage();


//(Example 2 : returning another promise)
console.log("1 is working");
console.log("2 is working");
  var AsyncFunction = async() => {
    var x = new Promise((resolve,reject) => {
        setTimeout(() => resolve("3 is working"), 3000);
    });
    var result = await x;
    return result;
  }
AsyncFunction().then(resolved => console.log(resolved));
console.log("3 is working");

Example 5: javascript async await

// The await operator in JavaScript can only be used from inside an async function.
// If the parameter is a promise, execution of the async function will resume when the promise is resolved
// (unless the promise is rejected, in which case an error will be thrown that can be handled with normal JavaScript exception handling).
// If the parameter is not a promise, the parameter itself will be returned immediately.[13]

// Many libraries provide promise objects that can also be used with await,
// as long as they match the specification for native JavaScript promises.
// However, promises from the jQuery library were not Promises/A+ compatible until jQuery 3.0.[14]

async function createNewDoc() {
  let response = await db.post({}); // post a new doc
  return await db.get(response.id); // find by id
}

async function main() {
  try {
    let doc = await createNewDoc();
    console.log(doc);
  } catch (err) {
    console.log(err);
  }
}
main();

Example 6: async await js

fetch('coffee.jpg')
.then(response => {
  if (!response.ok) {
    throw new Error(`HTTP error! status: ${response.status}`);
  } else {
    return response.blob();
  }
})
.then(myBlob => {
  let objectURL = URL.createObjectURL(myBlob);
  let image = document.createElement('img');
  image.src = objectURL;
  document.body.appendChild(image);
})
.catch(e => {
  console.log('There has been a problem with your fetch operation: ' + e.message);
});