How to add auto-reload to your Node JS app?

Kavin Desi Valli
·Sep 19, 2020·

3 min read

How to add auto-reload to your Node JS app?

Photo by Vladyslav Kuznietsov on Unsplash

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Table of contents

  • Setting up a node server
  • Disadvantage of this
  • Settings up nodemon to run the server

This is one of the first things I searched for, when I started learning Node JS with Express, since it was becoming too hard of a job to keep stopping and re-running the server, again and again. This is why, I use an npm package called nodemon

Setting up a node server

I hope you have NodeJS installed in your machine.

  • Let's setup the directory
    mkdir nodemon_tutorial && cd nodemon_tutorial
    
npm init -y

This would create a package.json

  • Now, let's install express to start a server
    npm install express
    
  • Now, let's create a file named index.js

    touch index.js
    
  • Open the folder in your favourite Code Editor. I use VS Code, so I will run:

    code .
    
  • Now inside index.js add the following

const express = require('express');
const app = express();
const port = process.env.PORT || 3000

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

app.listen(port, () => {
   console.log(`App is running at port: ${port}`);
})

Explanation of code

  • Line 1: In line 1, we are just importing the express package for running the server
  • Line 2: We are making an app, by instantiating the express module
  • Line 3: We are creating a variable for the port. It will search for an environment variable with name PORT. If it does not find any, by default, it assigns it to 3000.
  • Line 5-7: Here, we are just creating a route. So, if a person, sends a get request to /, then he will get Hello World as response
  • Line 9-11: We are just making the app run and listen on port variable Now, you could run this app, by simply saying
    node index.js
    

This will give the output

App is running at port: 3000
  • Now just go to your browser and type: localhost:3000/

Disadvantage of this

  • Now go to index.js and change "Hello World!" to "Hello, this is my first nodemon app!"
  • Now, even if you go to the browser and refresh, it will remain the same

Settings up nodemon to run the server

  • To install nodemon run:
    npm install nodemon --save-dev
    
  • We are adding --save-dev because we want this only in development and not while publishing it.

  • Now, go to package.json file and edit the following line:

- "test": "echo \"Error: no test specified\" && exit 1"
+ "start":"nodemon index.js"
  • So, what we are doing is that we are making nodemon run the server instead of node.
  • Now, terminate the server which was running and run:

    npm start
    
  • Now, go to localhost:3000

  • Try changing the response while getting / in the index.js and after you save it, the server should auto-reload. Now go to the browser and refresh again. You should see the new response
 
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