UTF-8 BOM causes error

[beakdoctor]

I just noticed if you have a file with a UTF-8 BOM standard will throw an error like:
test2.js:1:1: Irregular whitespace not allowed
Is this intentional? Either way it's a confusing error because you can't actually see it visually. Also, Visual Studio apparently loves to add these to your files which will cause a lot of headaches along with this rule.

[dcousens]

Can you post a file we can use for reproduction?
If you have trouble copy pasting it into GitHub, just paste the file base64 encoded.

[beakdoctor]

I can't attach any files for some reason, but here is the base64:
77u/dmFyIHggPSA0Mg0KbW9kdWxlLmV4cG9ydHMgPSB4DQo=

I have no idea if the bom is preserved, but there is another way. In npm there is a tool called add-bom:

> standard nobom.js


> add-bom -f nobom.js
BOM was appended to nobom.js

> standard nobom.js
standard: Use JavaScript Standard Style (https://github.com/feross/standard)
  C:\kod\oltest\VS-OL\VS-OL\src\nobom.js:1:1: Irregular whitespace not allowed

There is also another tool called strip-bom-cli that is invoked like this:

> strip-bom nobom.js > nobom2.js

> standard nobom2.js

>

[dcousens]

Bug confirmed.

@feross I'm guessing this is an eslint issue?

[Flet]

I believe this is a feature of the rule:
http://eslint.org/docs/rules/no-irregular-whitespace.html

With this rule enabled the following characters will cause warnings outside of strings:
\ufeff - Zero Width No-Break Space - <BOM>

[feross]

There's no need for a BOM character in a plaintext UTF-8 file. It's neither required, nor recommended by the Unicode spec.

It appears there's an option to disable this behavior in Visual Studio: https://stackoverflow.com/questions/5406172/utf-8-without-bom

[dcousens]

@Flet that'll teach me for not investigating what a BOM character is.
Not a bug.

[feross]

@dcousens Yeah, I hadn't heard of them before this either.