Introduction to Koa Js

What is koa js?

Koa.js is a flexible Node.js web application framework that provides robust web and mobile application features. Koa.js is a lightweight framework for building web apps and APIs. The framework’s features and technologies help programmers simplify the creation of web apps and APIs.

Let’s create a sample project using Koa.js

• Before we start to develop, we need to have installed Node and npm. Using this link we can install Node.js, https://nodejs.org/en/download/

Node Package Manager (npm)

• npm is a package manager for node. The npm registry is a public library of open-source code packages for Node.js, front-end websites, mobile apps, robots, routers, and a variety of other JavaScript needs. npm gives us access to all of these packages and allows us to install them locally.

• Using the following command you can check the installed version on node and npm.

> node --version
> npm --version

• You will get output like this,

Let’s go on the step by step.

Step 1:

• Here I used vs code to run this program. Create a new folder named hello-world.

Step 2:

• Open new ‘Terminal’ and run the following code to create a package.json file,

npm init

• It will request the following information from you.

Step 3:

• To install koa run the following code,

npm install koa

• To install nodemon run the following code,

npm install nodemon --save-dev

Step 4:

• Create a new file called app.js and type the following code,

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

app.use(function* (){
   this.body = 'Hello world!';
});

app.listen(3000, function(){
   console.log('Server running on https://localhost:3000')
});

• Save the file and type the following code in terminal,

nodemon app.js

• This will start the server. To test this app, go to https://localhost:3000 in your browser and you should see the following message.

Hope you learned something from this article.

Thank you!