Warn about JSX file extension

[gaearon]

Update

We support JSX extension since 0.4.1 even though we don’t recommend it.
Read the release notes.

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Original Thread

We don’t support it. AFAIK there is no good reason to: #87 (comment).

We should do two things:

• Document that.
• Provide a descriptive error when you attempt to import a JSX file. This should be fairly easy to do with a Webpack plugin. You can look at this project for inspiration (although obviously the solution will be different).

[tizmagik]

I'd like to work on this. I imagine the best way would be to publish a webpack plugin that takes some regex and error message as options to keep it configurable and potentially useful in other contexts. Does that approach make sense?

[gaearon]

Sounds reasonable.

[stephenkingsley]

I fix it~

[tizmagik]

Submitted #353

[gaearon]

@stephenkingsley Since @tizmagik first offered to work on this, let’s give him the opportunity to finish it?

@tizmagik I think it’s not just importing .jsx that we want to warn about. We want to warn if user imports ./App but only App.jsx exists. This is the most likely case—not that they will import ./App.jsx. So we should warn in that case. (We can check the imported extension with an ESLint rule instead, so it’s not as important.) You would want to hook into resolve mechanism like this plugin does and throw a different error.. I think.

[stephenkingsley]

We want to warn if user imports ./App but only App.jsx exists

I review @tizmagik code. when the webpack compile jsx file that we warn it. this is not you want? If had ./App.js and ./App.jsx, I think nodejs will importing ./App.js. I am a newbie, so I want to know what you want~

[gaearon]

I want the following to work:

• App.jsx exists but App.js does not
• User writes import App from './App' in another file
• We should warn

[stephenkingsley]

thx! I think @tizmagik is work too easy to fix this problem.

[stephenkingsley]

If have a solution that both have ./App.js and ./App.jsx in webpack compile? I think only have js or jsx file. so @tizmagik work I think it is ok. I want your suggestion again, please.

[gaearon]

I’m not sure I understand what you’re asking.

[stephenkingsley]

Sorry, my english is not good. User writes import App from './App'. if App.js exists and App.jsx also exists, I think webpack will import App.js file. I think this solution is right, we should not warn the User.but if App.jsx exists, App.js does not. we should warn the User. it's right?