I have a Node.js app that uses Express. In that app, I have a block that looks like this:

const app = require('./app');
const port = process.env.PORT || 8080;
const server = app.listen(port);

server.on('listening', () =>
  console.log(`Application launched on ${app.get('host')}:${port}`)
);

This successfully works. It successfully prints the message when the listening event is fired. My question is, is there any event I can listen for, for when my server is stopped / shutting down? Or when the server stops listening?

I would like to do some cleanup in this scenario.

I have a Node.js app that uses Express. In that app, I have a block that looks like this:

const app = require('./app');
const port = process.env.PORT || 8080;
const server = app.listen(port);

server.on('listening', () =>
  console.log(`Application launched on ${app.get('host')}:${port}`)
);

This successfully works. It successfully prints the message when the listening event is fired. My question is, is there any event I can listen for, for when my server is stopped / shutting down? Or when the server stops listening?

I would like to do some cleanup in this scenario.

• javascript
• node.js
• express

• Not sure why you're using backticks in your console.log entry. That seems like a mistake. – tadman Commented Apr 29, 2016 at 16:44
• 1 Also do you mean the exit event? – tadman Commented Apr 29, 2016 at 16:45
• 2 @tadman The backticks are es6 template strings. – Ad.Infinitum Commented Apr 29, 2016 at 16:58
• @Ad.Infinitum Learn something new every day. Thanks! – tadman Commented Apr 29, 2016 at 17:19
• sorry for going off-topic, but this is the first time I see someone with a reputation of 268 and 10 gold badges :P – Yerken Commented Apr 29, 2016 at 17:44

3 Answers 3

You could listen to node's process events for shutdown

// listen for TERM signal .e.g. kill
process.on ('SIGTERM', doSomething);

// listen for INT signal e.g. Ctrl-C
process.on ('SIGINT', doSomething); 

//or even exit event 

process.on('exit',doSomething); 

You should be able to trap this with exit:

process.on('exit', function() {
  console.log('Process terminating.')
});

As pointed out in the documentation you cannot defer anything, this is a one shot deal.

You can also use promises along the following lines to make everything nice and synchronous:

#!/usr/bin/env node
(async () => {
const express = require('express')
const app = express()
app.get('/', (req, res) => {
  res.send('hello world')
})
await new Promise((resolve, reject) => {
  const server = app.listen(3000, function () {
    console.log('Server started')
    // If you wanted to test this code, you could close it here.
    // this.close()
  })
  server.on('close', resolve)
})
console.log('After listen')
})()

Related: How to synchronously wait for express.js HTTP server to close after a listen call?