Introduction to Koa.js

 

       What is Koa.js

              When it comes to web development, you're almost certainly going to use a framework to get your backend API up and running. Apart from Node having better built-in mechanisms for building web servers, frameworks, on the other hand, make this job easier by providing good features like middleware, routing mechanisms, and so on.

     In the Node.js universe, Express by far is the leader in web development. Koa.js is another excellent choice that is gaining popularity. In terms of coding, Koa was developed to be smaller, quicker, and more expressive. Express is great for developing web APIs, but it lacks a bit of expressiveness and still forces us to commit some boilerplate code that we could avoid, as we'll see in practice in a few minutes.

By the end of this blog, we will learn how t0 displayed a simple text on your server.      

 

Setup and configuration

 

Make sure you have Node installed, then select a folder for this example's development and run the following commands 

npm init
npm i koa

   The koa dependency is the koa framework's heart. Expressive HTTP middleware framework for Node.js that makes writing web applications and APIs easier. Koa's middleware stack operates in a stack-like fashion, allowing you to perform tasks downstream before filtering and manipulating the response upstream. This includes things like the content negotiating process, node inconsistency normalization, redirection, and a few others. Koa does not include any middleware.

Now, at the root of your project, create a new app.js file. Add the following code in there:

const koa = require('koa');
const app = new koa();

app.use(async (ctx) =>{
   ctx.body = 'Hello Code Lovers';
});

app.listen(3000, () =>{
   console.log('Server running on port 3000')
});

   The first few lines of this listing are related to the imports of the dependencies we just installed. Koa must be instantiated using the new operator. The first line imports Koa to our file. The variable Koa gives us access to its API. It is used to create an application and assign it to the const app.

   app. use(function) is a middleware function that is called whenever our server receives a request. A generator is the callback function. In Koa, the context of this generator is referred to as context. The request and response objects are accessed and modified using this context. The body of this response is set to Hello Code Lovers.

   app. listen(port, function) binds to the specified port and listens for connections. The only required parameter here is port. If the app runs successfully, the callback function is called.

Save the file, then launch your terminal and type

$ nodemon app.js

  Then the server will be launched. To test this app, open your browser and navigate to https://localhost:3000; you should see the message below.

Conclusion

    This was only a brief introduction to the capabilities of Koa.js and how it can help with code organization.

Koa also supports CSRF and JWT (JSON Web Tokens), as well as access logs, charset conversions, caching, minifies and compressors, and many other features. Please see the official GitHub project for more information on these.

                                                         Best wishes!!!