Detecting CTRL+C in Node.js

Question

I got this code from a different SO question, but node complained to use process.stdin.setRawMode instead of tty, so I changed it.

Before:

var tty = require("tty");

process.openStdin().on("keypress", function(chunk, key) {
  if(key && key.name === "c" && key.ctrl) {
    console.log("bye bye");
    process.exit();
  }
});

tty.setRawMode(true);

After:

process.stdin.setRawMode(true);
process.stdin.on("keypress", function(chunk, key) {
  if(key && key.name === "c" && key.ctrl) {
    console.log("bye bye");
    process.exit();
  }
});

In any case, it's just creating a totally nonresponsive node process that does nothing, with the first complaining about tty, then throwing an error, and the second just doing nothing and disabling Node's native CTRL+C handler, so it doesn't even quit node when I press it. How can I successfully handle Ctrl+C in Windows?

Answer 1

If you're trying to catch the interrupt signal SIGINT, you don't need to read from the keyboard. The process object of nodejs exposes an interrupt event:

process.on('SIGINT', function() {
    console.log("Caught interrupt signal");

    if (i_should_exit)
        process.exit();
});

Edit: doesn't work on Windows without a workaround. See here

Answer 2

The NPM module, death, uses SIGINT, SIGQUIT, and SIGTERM.

So basically, all you need to do is:

process.on('SIGINT', () => {});  // CTRL+C
process.on('SIGQUIT', () => {}); // Keyboard quit
process.on('SIGTERM', () => {}); // `kill` command

As a side note, this may actually call SIGINT, SIGQUIT, and SIGTERM numerous times... not sure why, it did for me.

I fixed it by doing this:

let callAmount = 0;
process.on('SIGINT', function() {
    if(callAmount < 1) {
        send.success(`✅ The server has been stopped`, 'Shutdown information', 'This shutdown was initiated by CTRL+C.');
        setTimeout(() => process.exit(0), 1000);
    }

    callAmount++;
});

If all you want to do is detect the interruption keys, just use SIGINT

Edit: I didn't realize this post was very old, oh well, it's helpful to others I guess!

Answer 3

For those who need the functionality, I found death (npm nodule, hah!).

Author also claims it works on windows:

It's only been tested on POSIX compatible systems. Here's a nice discussion on Windows signals, apparently, this has been fixed/mapped.

I can confirm CTRL+C works on win32 (yes, I am surprised).

Answer 4

process.on('signal', async (signal) => {
    console.log('signal: ', signal);
    if (signal === 'SIGINT') {
        console.log('Received SIGINT. Calling save function...');
        await amazon.saveData();
    }

    process.exit(0);
});

Answer 5

if (event.key == "ctrl+c") {
    console.log("goodbye");
    break;
}