JavaScript async function

In this article, we will be covering all about the async function in JS and how to use the async function in JavaScript. Before jumping directly to the async function in JS, we will learn about JavaScript and the basics of what exactly an async word is in this context. So if you are new to all these concepts, don’t worry, we will be covering it right from the fundamentals and will then move to differences. So keep reading.

Introduction to JS

JavaScript is one of the most used languages when it comes to building web applications as it allows developers to wrap HTML and CSS code in it to make web apps interactive. It enables the interaction of users with the web application. It is also used for making animations on websites and has a large community on GitHub. JavaScript has tons of libraries, one of which is React which we will be covering in this article later. 

Use cases

• Building web server and its interactive functions
• Animations and graphics, adding special effects to web components
• Validating forms and exception errors
• Adding behavior and functionalities to web pages

In JavaScript, promises are used to handle asynchronous operations. When dealing with several asynchronous activities, where callbacks might cause callback hell and unmanageable code, they are simple to manage.

Important points to remember in JS

• It is a scripting language
• It has unstructured code
• It is a programming language
• It is used both client-side and server-side to make web apps interactive
• It is built and maintained by Brendan Eich and the team
• Uses built-in browser DOM
• Extension of JavaScript file is .js

We all know that JavaScript is synchronous, which means it contains an event loop that allows you to queue up an action that won’t happen until the loop becomes available after the code that queued the action has completed processing.

However, there are a number of features in our software that make our code asynchronous, one of which is the Async/Await capabilities. Async/Await is an extension of promises, which we get as a language feature.

To learn more about it, look up Promises in Javascript.

The parts that follow will go over async and await in further depth, as well as provide several examples (both separate and combined async-await examples):

Async function

It simply allows us to create promises-based code as if it were synchronous, while also ensuring that the execution thread is not broken. The event loop allows it to work asynchronously. A value is always returned by async functions. It ensures that a promise is returned, and if it isn’t, JavaScript wraps it in a promise that is resolved with the promise’s value.

const getData = async() => {
	var data = "Codedamn";
	return data;
}

getData().then(data => console.log(data));
Code language: JavaScript (javascript)

The await function is used to wait for the promise to be fulfilled. It could only be used in the async block. It forces the code to wait for the promise to return a result. It does nothing but makes the async block wait.

const getData = async() => {
	var y = await "Codedamn";
	console.log(y);
}

console.log(1);
getData();
console.log(2);
Code language: JavaScript (javascript)

It’s worth noting that the console prints two before “Codedamn.” This is because the await keyword is used.

Example: In this example, we’ll use a method to implement numerous promises, and then we’ll utilize that way to display our results.

function asynchronous_operational_method() {
let first_promise = new Promise((resolve, reject) => resolve("Hello"));
let second_promise = new Promise((resolve, reject) => {
	setTimeout(() => {
	resolve(" Codedamn.");
	}, 1000);
});
let combined_promise = Promise.all([first_promise, second_promise]);
return combined_promise;
}

async function display() {
let data = await asynchronous_operational_method();
console.log(data);
}

display();

Code language: JavaScript (javascript)

Conclusion

This is how async in JavaScript is used. If you have any feedback, do drop a text in the comment section.

This was all about the async functions in JavaScript. If you have any query related to React or JavaScript, do drop it down in the comment section also do check out codedamn courses if you want to learn more about JavaScript and React with its use cases and amazing projects. They also have an in-built playground for different programming languages and environment sets so do check that out and join codedamn’s community! 

Hope you like it.