In This Blog, you are going to learn one of the most important topics in JavaScript i-e Async And Await, Synchronous And Asynchronous Programming In JavaScript. For Performing asynchronous Operations then we can use promises and async and await in JavaScript.
Synchronous Programming
Asynchronous Programming
JavaScript Async And Await
- In JavaScript, there’s a special syntax to work with promises in a more comfortable fashion, called “async/await”. It’s surprisingly easy to understand and easy to use.
- In JavaScript, async and await make promises easier to write
- In JavaScript, async makes a function return a Promise.
- In JavaScript, the keyword async before a function makes the function return a promise.
Both Functions Are Same
Demonstration of Promise In JavaScript
Async Function
Async With Await In JavaScript
Important Points – Await & Async
- In JavaScript, await makes a function wait for a Promise
- In JavaScript, Promises introduced in es6 2015
- In JavaScript, Async & await introduced in es 2017
- In JavaScript, we don’t need to write resolve and reject inside async function because async function will take care of it.
- In JavaScript, the await keyword can only be used inside an async function, you cannot use await keyword inside a normal function.
Source Code
Async_Await.html File Code
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>ASYNC AND AWAIT</title>
</head>
<body>
<script>
// FETCH - CALLING API
// async function example()
// {
// console.log("hello 1");
// const data = await fetch("http://jsonplaceholder.typicode.com/posts");
// console.log("hello 2");
// const posts = await data.json();
// console.log("hello 3");
// return posts;
// }
async function example()
{
const data = await fetch("http://jsonplaceholder.typicode.com/posts");
const posts = await data.json();
return posts;
}
example().then((result) => {
console.log(result);
}).catch((msg) => {
console.log(msg);
});
// let a = example();
// console.log(a);
// console.log("hello 4");
// console.log("hello 5");
// async function example()
// {
// console.log("hello 1");
// await console.log("hello 2");
// console.log("hello 3");
// }
//
// example();
// console.log("hello 4");
// console.log("hello 5");
// async function example()
// {
// return "Hello World";
// }
//
// console.log(example());
// console.log("hello 1");
// setTimeout(() => {
// console.log("hello 2");
// },3000);
// console.log("hello 3");
</script>
</body>
</html>
Download Notes Of This Blog From the link given below
https://www.mediafire.com/file/2oz2kceouajrbx7/ASYNC+AWAIT.pptx/file
Download Source Code of This Blog From the link given below
https://www.mediafire.com/file/khdojli44rcoipy/ASYNC_AWAIT.html/file
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