Node: Require `.\` does not work on Windows

[wmcmurray]

Windows uses backslashes inside paths and it seems to be supported by the require function. BUT ! When you use a backslash inside the "current path syntax" (usually ./) it does not work. I found this using the require.resolve method directly.

Test case :

file /test/index.js :

var test, tests = [
  './stuff/please-require-me',
  './stuff\\please-require-me',
  '.\\stuff\\please-require-me'
  ];

for(i in tests){
  try {
    test = require(tests[i]);
  } catch(e){
    test = e.message;
  }
  console.log(tests[i]+' = ', test);
}

file /test/stuff/please-require-me.js :

module.exports = 'OK';

My test output :

$ node index.js
./stuff/please-require-me =  OK
./stuff\please-require-me =  OK
.\stuff\please-require-me =  Cannot find module '.\stuff\please-require-me'

As you can see in the second test, the backslash works, but in the third test it fails because it is in the "current path syntax".

Additional notes

I also made a quick check to see if the .\ is supposed to work, and it does :

C:\Users\William Mcmurray>cd ./Desktop
C:\Users\William Mcmurray\Desktop>cd ../
C:\Users\William Mcmurray>cd .\Desktop
C:\Users\William Mcmurray\Desktop>

Specs

• Version: v5.10.0
• Platform: Windows 10, 64-bit

[Fishrock123]

@wmcmurray Are you saying using require.resolve() directly does or doesn't work correctly?

cc @nodejs/platform-windows

[wmcmurray]

@Fishrock123 Both require('.\something') and require.resolve('.\something') doesn't work correctly.

[seishun]

https://github.com/nodejs/node/blob/a20c70029075cab18e4ff4d27dfd95b7eda2b268/lib/module.js#L229

I'm not sure it's a bug though. require is meant to be portable, and backslashes will only work on Windows. Also module loading API is locked.

[domenic]

Yeah, this is not a bug. Require doesn't take file paths; it takes module paths, which are /-delimited. \ in a module path is just an error and should always fail.

[wmcmurray]

@domenic Ok, that make sense. Then my second test (containing a \) should have failed too ? Adding a check to make that fail right now would be a relatively huge breaking change :confused:

[domenic]

Yeah, probably not worth it, so likely it's just going to stay inconsistent forever since we can't change it either way. But the intent is to only use /.

[jasnell]

Agreed. Closing.

[guybedford]

There's an interesting addendum here and that is that the URL specification permits \ characters being converted into / in module specifiers, so I think this handling between the .\\x and ./x\\y cases not working and working respectively is in full alignment with the browser spec.

[trusktr]

@guybedford If that the case, shouldn't both .\\x and ./x\\y pass? If not, then I'm confused and it is confusing.

[guybedford]

@trusktr in ES modules in browsers, .\\x is parsed as a bare specifier, and will always throw for no resolution instead of attempting to be fetched.