Building a JSON REST API with NodeJS and Express using Typescript

NodeJS and Express are popular tools for building backend APIs, and using Typescript can add even more power and type safety to your code. In this article, we will walk through the process of creating a JSON REST API using NodeJS, Express, and Typescript.

Setting up the project

First, we need to initialize a new NodeJS project and install the necessary dependencies. You can do this by running the following commands in your terminal:

      mkdir json-rest-api
      cd json-rest-api
      npm init -y
      npm install express typescript @types/express ts-node
    

Next, we need to set up Typescript in our project. Create a new file called tsconfig.json in the root of your project and add the following configuration:

      {
        "compilerOptions": {
          "target": "es5",
          "module": "commonjs",
          "outDir": "dist",
          "strict": true,
          "esModuleInterop": true
        }
      }
    

Creating the API

Now that our project is set up, we can start building our API. Create a new file called app.ts and add the following code:

      import express, { Request, Response } from 'express';

      const app = express();
      const port = 3000;

      app.get('/', (req: Request, res: Response) => {
        res.json({ message: 'Hello, world!' });
      });

      app.listen(port, () => {
        console.log(`Server is running on port ${port}`);
      });
    

This code sets up a simple Express server with a single route that returns a JSON response. Now, we can compile our Typescript code to Javascript by running the following command:

      npx tsc
    

After running this command, a new folder called dist will be created in your project, containing the compiled Javascript code. You can now start your server by running the following command:

      node dist/app.js
    

Now, you have a simple JSON REST API up and running!

Conclusion

In this article, we have learned how to build a JSON REST API with NodeJS and Express using Typescript. This combination of tools allows for powerful and type-safe backend development. By following the steps outlined in this article, you can create sophisticated APIs with ease.