JAVASCRIPT

async javascript

(async () => {
  let response = await fetch('/article/promise-chaining/user.json');
  let user = await response.json();
  ...
})();

// (BONUS CODE) await with promise
await new Promise(resolve => setTimeout(resolve, 1000))
console.log('Hello!') // 1 seconds after sended console.log

javascript async script

<script async src="script.js"></script>

async function

const foo = async () => {
   await// do something
}
// OR
async function foo() {
  await// do something
}

Define an async function

const yourAsyncFunction = async () => {
    // do something asynchronously and return a promise
    return result;
  }
  
anArray.forEach(async item => {
   // do something asynchronously for each item in 'anArray'
   // one could also use .map here to return an array of promises to use with 'Promise.all()'
 });
 
server.getPeople().then(async people => {
  people.forEach(person => {
    // do something asynchronously for each person
  });
});

async await in javascript

 const showPosts = async () => {
 const response = await fetch('https://jsonplaceholder.typicode.com/posts');
 const posts = await response.json();
 console.log(posts);
}

showPosts();

javascript async/await

//ORIGINAL
//each .then() returns a promisse and can be chained. The .then() will run after the previous one has finished. It emulates an async/await behavior.

fetch('https://jsonplaceholder.typicode.com/users')//fetch the content
  .then((response) => response.json())//then use that content and convert it to a javascript object
  .then(users => {
    const firstUser = users[0];
    console.log(firstUser);
    return fetch('https://jsonplaceholder.typicode.com/posts?userId=' + firstUser.id);
  })//then return the content from posts related to that user ID
  .then((response) => response.json())//then use that content and convert it to a javascript object
  .then(posts => console.log(posts));//then log the result


//ASYNC/AWAIT
const myAsyncFunction = async () => {//define that this will be asynchronous
  const usersResponse = await fetch('https://jsonplaceholder.typicode.com/users');//wait for the fecth result and put it in the variable
  const users = await usersResponse.json();//wait for the previous item to be done, transform it into a javascript object and put it in the variable
  const secondUser = users[1];

  console.log(secondUser);//then log the result

  const postsResponse = await fetch('https://jsonplaceholder.typicode.com/posts?userId=' + secondUser.id);//wait for the previous item to be done, wait for the fecth result and put it in the variable
  const posts = await postsResponse.json();//wait for the previous item to be done, transform it into a javascript object and put it in the variable

  console.log(posts);//then log the result
}

myAsyncFunction();

what is an async function

// Old School Javascript Invoke
(async function() {
	await someAsyncFunction();
})();

//New ES6 Javascript Invoke
(async () => {
	await someAsyncFunction();
})();

//Example (async & await)
function delayResult() {
 return new Promise(resolve => {
   setTimeout(() => {
     resolve(‘Done’);
   }, 5000)
 })
}
async function getResult() {
 let result = await delayResult();
 return result;
}
getResult();

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

data();

script async syntax

<script src="demo_async.js" async></script>

async function javascript dec

  const mapUrl = 'https://';

(async (getUrl) => {
   const response = await fetch(mapUrl);
    const data = await response.json();
    console.log(data);
})();

async function javascript

//Async function (JAVASCRIPT)
//async function have 1 main purpose:

//Being able to use 'await' in a function
function example() {
return await fetch('https://mysite.com/api'); //error
}

async function smartexample() {
return await fetch('https://mysite.com/api'); //mhmm!
}

example of async and await in javascript

// example of async and await in javascript
// First create promise
let myPromise = () => {
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      resolve('Yay, I resolved!')
    }, 1000);
  });
}

// async without await keyword
async function noAwait() {
 let value = myPromise();
 console.log(value);
}
 
// async with await keyword
async function yesAwait() {
 let value = await myPromise();
 console.log(value);
}
 
noAwait(); // Prints: Promise { <pending> }
yesAwait(); // Prints: Yay, I resolved!

javascipt async

const asyncExample = async () => {};

JavaScript Async

function myFunction() {
  return Promise.resolve("Hello");
}

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);
});

Javscript Async Function

// async function example

async function f() {
    console.log('Async function.');
    return Promise.resolve(1);
}

f();