Node.js Cookbook

What is this?

A cookbook for getting started with node.js development fast! It's based on the excellent tutorials written by Robin Wieruch.

If you're a Java developer and want to start developing with node.js, you've come to the right place... maybe. ;-)

Usage

There are 3 versions of the app that can be run:

1. npm run start-stub-nonmod - Run Express app with stubbed model and non-modular routes.
2. npm run - Runs Express app with stubbed model and modular routes.
3. npm start - Runs Express app with MongoDB backed model and modular routes.

Call the endpoints, e.g.

• http://localhost:3000/users/1
• http://localhost:3000/messages/1

How does stuff work?

npm versioning

Node Package Manager is used to manage node.js dependencies. A bit like Maven and Gradle.

The package.json contains the project's dependency info.

npm uses semantic versioning for dependency management:

• ~1.0.4 - only take patch updates.
• ^1.0.4 - only take minor updates (+ patch updates).

Run npm install to install all the dependencies in package.json - do after checking out of Git.

Run npm outdated then npm update and to check if we're up to date.

npm install express --save - installs and updates prod deps in package.json.

npm install jest --save - installs and updates dev deps package.json.

Nodemon

Runs the app in the background when you're developing, so that changes to the code are reflected immediately.

npm install nodemon --save-dev

Update pacakge.json script:

  "scripts": {
    "start": "nodemon src/index.js",

Babel

Used to transpile latest JavaScript into simpler JS for node.js engine to execute. Allows developers to use latest ECMAScript features and run them on node.js.

npm install @babel/core @babel/node --save-dev

Update your pacakge.json scripts start line with:

"scripts": {
    "start": "nodemon --exec babel-node src/index.js",

Next, you need to tell which features (presets) of ECMAScript to use:

npm install @babel/preset-env --save-dev

Create a .babelrc file in project root and add:

{
  "presets": [
    "@babel/preset-env"
  ]
}

Express

A very popular HTTP server for node.js. Excellent support for creating REST endpoints. Bit like Spring REST Coontrollers.

Routes

Essentially a REST endpoint.

const app = express();

app.get('/', (req, res) => {
  res.send('Hello World!');
});

Middleware

Bit like servlet filters in the Java world.

Application-level middleware

Can be 3rd party libs or custom impl. Applied at the application level.

For example, to allow CORS for entire app (adds CORS header). Instead of adding it for every route, it can be done once at the app level.

npm install cors

import cors from 'cors';

const app = express();

app.use(cors());

Another example is well-known middleware for parsing HTTP POST requests into JSON:

npm install body-parser

import bodyParser from 'body-parser';

app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: true }));

Router-level middleware

Runs only for a specific route.

TODO: Include example...

Environment Variables

Use dotenv to access them. Store your env vars in a .env file in project root folder.

npm install dotenv

import 'dotenv/config';

console.log(`Example app listening on port ${process.env.PORT}!`),

MongoDB

The app uses MongoDB for the database.

• How to install MongoDB on Debian: https://docs.mongodb.com/manual/tutorial/install-mongodb-on-debian/
• How to install MongoDB on MacOS: https://www.robinwieruch.de/mongodb-macos-setup/

Mongoose

The app uses Mongoose for ORM (Onject Relation Mapping) mapping layer.

npm install mongoose --save

It maps a JavaScript object model to a MongoDB schema. The model can then be used by the routes to fetch users, delete messages, etc.

REST API test tools

Curl

Use curl on the linux command line. Responses can be piped into Bash jq for formatting.

Example curl requests:

curl http://localhost:3000/messages | jq; # defaults to GET

curl -X DELETE http://localhost:3000/messages/msg_123

curl -X POST -H "Content-Type:application/json" http://localhost:3000/messages -d '{"text":"Hi again, World"}'

Postman

Use Postman.

Useful VS Code Extensions

VS Code is a decent free IDE for JavaScript development. Some useful extensions include:

1. DotEnv
2. ESLint
3. Prettier
4. GitLens
5. Jest vs Jest Runner - which is best?
6. Docker
7. TODO Tree
8. HCL (HashiCorp Language support for Vault config)

References

1. https://www.robinwieruch.de/mongodb-express-node-rest-api - a great series of tutorials for getting started with node.js, express, and MongoDB integration.