Creating Your First ‘Hello World’ Application with Fastify

Hello, I am Charu from Classmethod. I have recently started using Fastify in my projects so I thought of writing the basic start in a blog.

Introduction

If you got interested in this blog, then I am sure you are familiar with Node.js development, also you know a bit about Express or have worked with it. Well, Fastify is a NodeJS framework used for backend web development. It is mainly know for it's speed, efficiency, and developer experience.

Alongside, we'll explore TypeScript, a superset of JavaScript, renowned for its robust typing system and suitability for large-scale applications.

Prerequisites

Node.js installed.

Basic knowledge of TypeScript and Node.js.

An IDE or text editor of your choice (I am using VSCode).

Setting Up Your Project

Create a new directory for the project and initialize a Node.js project: 'npm init'

Install Fastify: 'npm install fastify'

Next, install TypeScript and necessary types: 'npm install typescript @types/node --save-dev'.

Getting started with the code

Make a new directory 'src' and a new file under 'src' directory. I named it as 'source.ts'.

Write the following code in source.ts file,

const fastify = require("fastify")({ logger: true });

fastify.get("/", async (request: any, reply: any) => {
  return { greeting: "Hello from Fastify and TypeScript!" };
});

const start = async () => {
  try {
    await fastify.listen({ port: 8888 });
  } catch (err) {
    fastify.log.error(err);
    process.exit(1);
  }
};

start();

The code above demonstrates a basic Fastify server with TypeScript that listens on port 8888. It defines a single route that responds to GET requests on the root path with a JSON greeting message. The fastify.listen({ port: 8888 }) call makes the Fastify server listen for incoming connections on port 8888. If there's an error starting the server, the error is logged, and the process exits with a status code of 1. Finally, the start function is called to start the server.

Make sure to check you package.json file start script. It should have the location of your js source file. In my case it is,

"scripts": {
    "build": "tsc",
    "start": "node dist/source.js",
}

Also, check your Typescript module in tsconfig.json file. It should be 'commonjs' as shown below,

"compilerOptions": {
        "target": "es2018",
        "module": "commonjs",
        "moduleResolution": "node",
        "outDir": "./dist",
        "esModuleInterop": true,
        "strict": true,
        "skipLibCheck": true,
    },

Now, to run your application, execute the following two commands-

npm run build

npm run start

You can visit your localhost in your browser and check the response. It should display the following response-

This was a basic example for your to start with Fastify. Hope you found it useful.

Thank you for reading!

Happy Learning:)