Benefits of Asynchronous Programming in Javascript

JavaScript is a single-threaded synchronous language by default, this simply means that an executed function must first be completed before the next function is executed. This fundamental behavior isn’t a problem for simple javascript applications but could cause a problem in larger apps with complex functions that perform long complex calculations. Since all operations and user interface (UI) rendering are performed on the same thread (UI thread), long-running functions will make your UI unresponsive which is bad user experience (UX). This is why the usage of asynchronous (or async) functions are really important in JavaScript as they do not block the execution of your entire code. Let us take a look at the meaning of functions and of some benefits of async functions below.

What are the Functions?

A  function is a block of code designed to perform a particular task. A function is usually only executed when something invokes it (calls it). The only exceptions are immediately invoked functions expressions (IIFE). An async function is a function that is executed in a separate order via the event loop and returns a promise as its result. These are different from workers (service workers, web workers, etc) that are executed in a different thread without access to DOM manipulation Apis.

Benefits of Asynchronous Functions

• Non-blocking Execution
  Async functions are executed via the event loop and as a result, the entire program can continue running regardless of its completion. This behavior is especially useful when waiting for a server response from an API call. Javascript also has some default async functions like setTimeout(), setInterval() etc.
• Faster execution Since the execution of your program is not blocked by async functions, what you have at the end of the day is an overall faster and more responsive application especially on the UI front which will translate to better UX for users.
•  Great for data-intensive apps
  Asynchronous programming in JavaScript (node.js) offers a non-blocking I/O (Input/Output) which is great for data-intensive apps since it is capable of serving multiple requests and access to data concurrently on a single thread. This simply means that an application accessing data asynchronously will not have to wait for the request to complete before processing other requests. This is very important in large scale real-time apps (for example messaging apps, media streaming apps, etc.) that serve multiple requests by multiple users to the same resources.

Wait a Minute
As great as the concept of async functions and programming are, they are not necessary for all situations and the only time it is really needed is during the execution of an intensive calculation or long-running functions and there are cases where they might cause problems in your application. For example, if other functions in your application require the result from the async function to run, executing them anyway when the async function is not completed will cause errors in your code. In cases like these, it is favorable to wait until the function has returned an output before proceeding with the execution of your code.