feat: "write" keystroke event in process.stdin

[tony-go]

What is the problem this feature will solve?

Hey Node.js family 💚

The purpose is to be able to simulate user keystrokes in process.stdin.

What is the feature you are proposing to solve the problem?

I observed that we could switch stdin to rawMode and listen for keypress events. Try to run this piece of code:

process.stdin.setRawMode(true);

process.stdin.on('keypress', function(str, key) {
  if (key.sequence === '\u0003') {
    process.exit();
  }

  console.log(str, key);
});

Now, press the right arrow of your keyboard and you should observe in the console:

undefined
{
  sequence: '\x1B[C',
  name: 'right',
  ctrl: false,
  meta: false,
  shift: false,
  code: '[C'
}

So, the idea is to be able to pass/write/append this keystroke event into process.stdin:

process.stdin.setRawMode(true);

// with `.write` API
process.stdin.write('\x1B[C', { keyevent: true }); // with sequence
process.stdin.write('[C', { keyevent: true }); // with code

// with a new `.emitSequence` API, only available in raw mode
process.stdin.emitSequence('\x1B[C');

// with a new `.emitCode` API, only available in raw mode
process.stdin.emitCode('[C');

// with a new `.emitEvent` API, only available in raw mode
process.stdin.emitEvent({
  sequence: '\x1B[C',
  name: 'right',
  ctrl: false,
  meta: false,
  shift: false,
  code: '[C'
});

(Maybe the .writeAPI should be reserved for String of Buffer, I probably make some confusion here, sorry for that)

What alternatives have you considered?

During my search, I found this tool: https://github.com/jordansissel/xdotool (and found a Node.js binding).

But I thought that it should more convenient to have it in Node.

[bnoordhuis]

Do I summarize correctly you want a way to inject key strokes?

I won't bore you with details but this is one of those seemingly simple things that gets horrendously complex in practice. I don't see Node.js adopting a general solution because you're usually better off with a narrower scoped custom solution like xdotool.

[tony-go]

Hey @bnoordhuis 👋

Thanks for your answer 🔝

I have already tried to take a look at xdotool (I know that a binding already exists for node), but it was not obvious that I could solve my problem with it. I'll spend more time on it a give an update here.

I won't bore you with details

Please do ^^ Before sending this issue I was thinking that I mixed up apples and pears. Please let me know if it's the case :)

[bnoordhuis]

So, one problem is that xdotool works on a completely different level (the X protocol) than the tty.

Key stroke injection for ttys is restricted to the byte-at-a-time TIOCSTI ioctl and that's sometimes disabled for security reasons (example), requires root privs when the tty is not your controlling tty, may not honor line discipline, etc.

And that's Unices. Windows is its own can of worms.

[tony-go]

@bnoordhuis Thanks a lot for these insights ^^

[github-actions]

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[github-actions]

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