Reload Express.js routes changes without manually restarting server

I use express.js, normally start server by

npm start

with Nodemon installed, I use

nodemon --exec npm start

Note: nodemon app.js will NOT work here,

because express.js use start script

To install nodemon

npm install -g nodemon

I think Nodemon has what you're looking for.

Nodemon is a utility that will monitor for any changes in your source and automatically restart your server. Perfect for development.

Example invocation:

nodemon index.js

You can livereload both front and backend changes to the browser using 'livereload', 'connect-livereload', and 'nodemon'. Also, this way you don't need Gulp or Grunt. Here's how they work together:

• livereload opens a high port and notifies the browser of any changed file
• connect-livereload monkey patches every served HTML page with a JavaScript snippet that connects to this high port
• nodemon restarts the server on any changed backend file

Set up livereload in Express

Set up Express to both start livereload server watching the public directory and ping the browser during nodemon-induced restart:

const livereload = require("livereload");
const connectLivereload = require("connect-livereload");

// open livereload high port and start to watch public directory for changes
const liveReloadServer = livereload.createServer();
liveReloadServer.watch(path.join(__dirname, 'public'));

// ping browser on Express boot, once browser has reconnected and handshaken
liveReloadServer.server.once("connection", () => {
  setTimeout(() => {
    liveReloadServer.refresh("/");
  }, 100);
});

const app = express();

// monkey patch every served HTML so they know of changes
app.use(connectLivereload());

Start Express with Nodemon

Start the server with nodemon, for example, with a dedicated watch script by running npm run watch.

The key point here is to ignore the public directory that's already being watched by livereload. You can also configure files with non-default extensions, like pug and mustache, to be watched.

"scripts": {
  "start": "node ./bin/www",
  "watch": "nodemon --ext js,pug --ignore public"
},

You can read a longer explanation in "Refresh front and backend changes to browser with Express, LiveReload and Nodemon."