Asynchronos and Synchronos Programming in Detail
Tags: javascript, webdev, react
Published: 2021-08-14 00:53:57

In this article, we will discuss What Synchronous Programming is? What is Asynchronous Programming? And whether JavaScript is Synchronous or Asynchronous?

Many developers struggle to understand topics like Callbacks, Promises, and Async/Await. One of the reasons may be not understanding the actual need and core logic behind them.

Having a good understanding of this topic can help you grasp them more easily.

##How Asynchronous Programming Works

An asynchronous function is typically used to make an API call. 
Applications can also use them to create a delay in a user's activity takes longer. Why would you want to make an app run slower? Because computers can perform tasks at a breakneck speed, the results might be disorienting to users.

As a result, the application's designers deliberately slow it down. It can send a message to another user nearly instantaneously. The loading circle isn't always an essential indicator that the message is taking too long to send. Instead, it's there to help users better grasp what's going on and feel more at ease with the software.

Yes, it can take a few seconds for a message to be sent due to network delays. Before a message is sent across a network, it must first be encoded on the user's device.

Items on the screen can appear and disappear instantly. It is through animations that help a user follow what is happening on the user interface. Animations can be asynchronous because other functions can be operating in the background. At the same time, they perform their operation over a while.

##When should asynchronous functions be used?
Asynchronous communication isn't always the best option. Asynchronous programs add complexity to the code and make it more challenging to read. Young programmers frequently overuse async functions in the mistaken belief that they provide a safeguard to ensure that their code runs correctly at runtime.
A general rule for when to use async functions:
Suitable for: Tasks that may take a long time to complete; high iteration.
Bad for: Simplicity.

When there are many iterations or the processes within the loop are complex, asynchronous loops are required. However, there is no reason to overcomplicate things by implementing a sophisticated recursive function for simple tasks like iterating through a small array. A basic synchronous for/while loop would suffice, plus it will be faster and easier to read.


##How does Synchronous Programming Works?
Synchronous programming is a programming paradigm in which operations are carried out in sequential order. Asynchronous programming is incompatible with this approach. Operations are carried out one after the other under this model. When the current step has completed execution and returned an outcome, the program advances to the next step. Long-running operations will "block" due to this linear nature, and the program will halt for the time it takes to perform them.

Steps defined consecutively occur in the same order in synchronous programming. As a result, a program that calls a synchronous function a() and uses the result in a function b() must be written in the order a; the primary function comes before b, the secondary function. The app will know the result of the primary function to the runtime by the time the flow of control reaches the secondary function.

Synchronous web programs load resources in a single, sequential order. If a higher-level resource or component fails to load, those below it will not respond.
A multi-threaded protocol is used to process synchronous requests.

Note: In programming, a thread is a single end-to-end worker or channel that handles requests.

In synchronous programming, each of these threads handles requests independently. As a result, each thread has its own execution time and must fully load before proceeding to the next event. As a result, executing the event on a thread locks up other threads, thus halting the entire user interface.
Web programs that rely only on synchronous programming typically load resources in a lock. Every action, including POST and GET requests, must always be loaded from scratch for each request and response.

As a result, synchronous calls guarantee that a client or browser receives a response to the first request before moving on to the next. This can lead to unnecessarily long wait times and a bad user experience.

##Examples of Asynchronous and Synchronous Programming

###Real-World Examples
Here are two real-world comparisons for people looking for a different method to comprehend their differences or a creative way to describe them to a friend.

Synchronous: You're in the mood for a burger and decide to visit McDonald's. You'll be prompted to wait while your burger is prepared after placing your order at the counter. You're locked at the counter until your burger is served in this synchronous circumstance.

Asynchronous: You're in the mood for a burger and decide to visit Five Guys. You approach the counter and place an order for a burger. Five Guys provides you with a buzzer that sounds when your burger is ready. You have a bit more freedom while waiting in an asynchronous condition.

Disclaimer: To be clear, we're not evaluating McDonald's or Five Guys' performance; this is imaginary.

There is no inherent advantage to one form of programming over another. Both Asynchronous and Synchronous programming are merely different, each with its own set of benefits. They're used in different situations. Depending on what you're building, you can and probably will use both sync and async tasks.

###Technical Examples
We have selected four common examples of when synchronous and asynchronous processing is used in applications.

Synchronous Processing
User Interfaces: The majority of user interface (UI) designs are synchronous. Because user interfaces are places where humans and computers interact, it's natural for them to mimic the communication norms and practices that people are used to. 
HTTP APIs: Asynchronous queries and responses are passed using HTTP APIs. Client programs that send HTTP queries anticipate a quick response from the webserver.

Asynchronous Processing
Batch-processing: is an asynchronous data-processing approach for handling enormous volumes of data. Large batches of data are handled at predetermined times with asynchronous batch processing to avoid clogging computing resources.

Long-running tasks: Asynchronous tasks, such as fulfilling an order placed on an e-commerce site, are best handled this way. While this task is being completed, there is no need to block resources.


##Pros and Cons of Synchronous and Asynchronous Programming

While asynchronous programming may appear to be the winner, in this case, both strategies have advantages and disadvantages. Then, using one or the other is a matter of personal preference or the nature of the problem at hand.
They are, nonetheless, superior to one another in a variety of ways. Let's have a look at the advantages and disadvantages of each of these programming approaches. Being synchronous all of the time can also be negative. For example, if your program has many time-consuming lines of code, it will become substantially slower. Because JavaScript is single-threaded, asynchronous IO call blocks the entire thread. Let's have a look at what this entails.


##Pros of Asynchronous Programming

Each script is loaded one by one, translating to improved performance, responsiveness, and user experience.
It reduces the time it takes for a page to load. As a result, future page refreshes aren't required while executing new requests.
Multiple features can be used at the same time, even if other requests are still in progress.
Asynchronous apps are very scalable and demand a tiny number of resources to run.
Even if one request takes a long time to react, it has no bearing on the time it takes for others to respond.
The failure of one thread does not affect the rendering of the others.
Customize error messages with built-in callbacks.

##Cons of Asynchronous Programming
It necessitates a large number of callbacks and recursive procedures, which can be time-consuming to develop.
There's no way for a user to know if a request succeeds or fails if callbacks aren't used appropriately, especially when making POST queries.
Your experience may be harmed by latency in the initial page render.
Asynchronously loaded web apps might be challenging for search engines like Google and Bing to crawl.
In some computer languages, asynchronous scripting may be challenging to accomplish.
It's easy for code to get jumbled and difficult to debug.

##Pros of Synchronous Programming
It necessitates minimal coding expertise and is compatible with all programming languages.
Even if you don't have any custom callbacks for request failures, you'll notice right away because the client (browser) handles such errors by default.
It performs better when performing CPU activities.
Synchronous web pages are more accessible for search engines to crawl.
It is an excellent tool for making simple requests.
Synchronous Programming's Drawbacks
The loading process can be lengthy.
There is no callback methods built-in.
When a thread is locked, other threads are also blocked.
The inability to do numerous actions at once may degrade the user experience.
When a request fails, the software as a whole becomes unresponsive.
A large number of resources may be required.

##Conclusion
Asynchronous and Synchronous function are one of the very basic of Programming languages and very easy to understand. I hope with this article you are able to have a full understanding of how Asynchronous function works. 

In my next article we would make an Asynchronous  and a Synchronous using Javascript. 

Thanks for reading.