• Setting up package.json and install related dependencies
• Setup and listen to server
• Organizing routes

Setting up package.json and install related dependencies

• First and foremost, we can create a package.json file by opening the terminal (Ctrl + `) in Visual Studio Code and initializing the npm (npm init)
• After the package.json file is created. We can then install the 2 dependencies which are going to be used in this article. Express in main dependency and Nodemon in dev dependency. Highly recommend Nodemon module which allow us to auto update the changes in our server without restarting it.
• Kindly add a new script command as "server": "nodemon <your main js file>" and create a new javascript file according to the value of main: property. In my case will be server.js

Then you should see your package.json file look something like this.

Setup and listen to server

To create a node server with express framework is quite straight forward.

const express = require('express');
const app = express();

app.get('/', (req, res) => {
    res.send('Server is running')
})

app.get('/test', (req, res) => {
    res.send('This is the test endpoint route')
})

app.listen(process.env.PORT || 5000, () => console.log(`Server has started. at PORT 5000`));

Explanation

1. Access the express module by calling require('express')
2. Config a server and assign into a variable const app = express()
3. Serve the http request according to different endpoint. Note: You can observe the response message Server is running by heading to http://localhost:5000 or This is the test endpoint route by heading to http://localhost:5000/test
4. Last but no least, config the listening port to the server. process.env.PORT || 5000 means it will auto assign random port number if the port 5000 is not available

Organizing routes

Imagine if there a tons of api we need to handle. It will be very messy if we combine all of them into one server.js file.
In this case we can orgranize them into different folder according to their endpoint referer.
For example now we have different categories of endpoints such as http://localhost:5000/user/profile and http://localhost:5000/plan/premium. We can then assign them into different directory as shown in below

Then we can add middleware to serve these api according to different directory.
server.js

app.use("/plan", require('./routes/plan'))
app.use("/user", require('./routes/user'))

user.js

const express = require('express');
const router = express.Router()

router.get('profile', (req, res) => {
    res.send("user profile endpoint route") //You should see this message if you type 'http://localhost:5000/user/profile' in browser
})

module.exports = router

plan.js

const express = require('express');
const router = express.Router()

router.get('premium', (req, res) => {
    res.send("plan premium endpoint route") //You should see this message if you type 'http://localhost:5000/plan/premium' in browser
})

module.exports = router