Getting started backend development with KoaJS and REST API’s.

When we talk about the modern-day web development it is something clear that JavaScript is one of the main languages which is used for the web development as well as the mobile development. The usage of this language or the technology has been gradually increased with the development of the JavaScript frameworks. So, talking about JavaScript and related technologies NodeJS is a one of the main backend technologies that we can find more popular with the developers. NodeJS is a cross platform, backend JavaScript runtime environment which runs on the v8 engine in order to execute JavaScript code outside the browser. So, from here onwards let’s talk about the KoaJS.

What is KoaJS?

KoaJS is an open source NodeJS framework which was developed by the team behind the Express. According to the KoaJS official website their aim to be more smaller, more expressive and more robust foundation for web application API. KoaJS uses asynchronous functions while it focuses on eliminating callbacks and to improve error handling.

Let’s make it more simpler going through process of creating a small application.

Let’s create a small application using KoaJS

Before we are going to start working with KoaJS, we need to make sure we have installed node and the version of the NodeJS should be v7.6.0 of higher for ES2015and async function support.

Once we installed NodeJS with the necessary requirements we can move forward and create a node package and install koaJS by following the given commands.

Once the koa is installed, then we can start working with our application. The rest is also a pretty simple process because only thing we have to do is to import the necessary modules and use them. In this case the main module that we have to deal with is koa. So we can import it and use it as the following code snippet.

Now we have finished creating our application and it is running on port 3000. We can use the listen method with the use of the Koa module. So in this process we are running on the port 3000. The port number is something optional since you can use any other port number you like. We can run this application and check whether it is working by typing the given command.

In this case index.js is the file name that you are doing your implementation.

As the next step we can add routing to our application. As an important thing in feature we need to understand that koa does not handle routing by default. So, in order to use it we need to install necessary middleware libraries for routing. We can simply install it with the following command given below.

Once we install the koa router, we can import it and use it in the same way imported koa to our application. But in here there is one more important thing to do. In order to use the routes, we need to register them. We can register the routes by the following few lines of code. So when ever we are going to import rout file to the index.js file, we need to register them in order to use them.

To proceed with the rest of the implementation we need to understand the concept of the context.

What is context in koa?

The simple idea of the context is it holds the request and the response objects into a single object where we can use the methods to writing web applications and API’s. when we are developing the HTTP server development a context will be created per request. When we want to access each request and the response, we can access them by the given code example. Other than the request and the responses there are many accessors and alias request equivalents and response equivalents.

Ex –

Request — ctx.header, ctx.path, ctx.url …etc.

Response — ctx.status, ctx.message, ctx.type …etc.

As the next step we can start working with the response handling part. We can just simply create the route by using the context that we have discussed moment ago. In the below example as we can see we have created a simple get rout with a simple message of “Hello world”. As we discussed earlier, in here context.body represent the response we are going to get when we call this request. Other than the response body we can define the status of the response as well.

So the full implementation will be the given below example.

What are the advantages and the disadvantages of Koa?

Advantages

· Light weight

· Improved error handling

· More manageable and clean async code implementations

· More improved interoperability and robustness

· Better user experience

· Better performance with no callbacks and better error handling

Disadvantages

· Not compatible with express-style middleware

· Usage of generators which are not compatible with other NodeJS framework middleware.

· Smaller community

In this article I have talked about the basics of koaJS and how start working with koaJS as an developer. We also have express which is kind of similar to koa with some major differences. For someone who is already familiar with express, this article will be a better place to get the base idea and start working with koa. For other also can have a good understanding about the koa and also can visit to the koa official website to read the documentation to get the complete idea about it. Thank you!