Readline keypress event is triggered only after pressing Esc key 3 times

[sindresorhus]

• Version: 6.2.2 and 4.4.5
• Platform: macOS 10.11.5
• Subsystem: readline

Test case

const readline = require('readline');
readline.emitKeypressEvents(process.stdin);
process.stdin.setRawMode(true);
process.stdin.on('keypress', console.log);

Expected

After pressing Esc once, I would get this output:

undefined { sequence: '\u001b',
 name: 'escape',
 ctrl: false,
 meta: true,
 shift: false }

Actual

After pressing Esc three times, I get this output:

undefined { sequence: '\u001b\u001b\u001b',
 name: 'escape',
 ctrl: false,
 meta: true,
 shift: false }

It works fine on 0.10.44 and 0.12.13. After pressing Esc once:

{ name: 'escape',
 ctrl: false,
 meta: false,
 shift: false,
 sequence: '\u001b' }

Also notice that meta is false here.

[MylesBorins]

I've dug into this a bit and can confirm the bug exists in v4.x and v5.x

It would appear to have been introduced in v2.0.2 I'll dig into that release and see where it came from

[MylesBorins]

So it would appear that escape started acting weird after aed6bce906 landed.

Doesn't appear to be easily revertable... I'm digging into what is going on with escape

[MylesBorins]

Found the offending section

https://github.com/nodejs/node/blob/master/lib/internal/readline.js#L144-L151

The original PR introduced this logic which yields to more results if the first character is an escape... which is problematic if your entire payload is an escape. It allows for double escaped characters, which is why things work on the third press

Not sure the best way to approach this, but I'll revisit in the morning

[princejwesley]

@thealphanerd It was mentioned in the PR itself.

[MylesBorins]

@princejwesley sigh... I wish I had read the pr instead of just the commit and then digging into the code.

@cjihrig you have the blame on most of internal/readline.js would you specify this as a wont-fix rather than as a bug?

[princejwesley]

@thealphanerd I'll fix it!