Support webpack.config.ts

[Ailrun]

Support request summary

Webpack supports something like webpack.config.ts with https://github.com/js-cli/js-interpret, as they mentioned in https://webpack.js.org/configuration/configuration-languages/.
However, in storybook, it detects fixed webpack.config.js in https://github.com/storybooks/storybook/blob/8757938b4104e96e4d33c292329222cdd3a68e98/lib/core/src/server/config.js#L89
This makes it hard to centralize webpack config, when I use webpack.config.ts.

Please specify which version of Storybook and optionally any affected addons that you're running

• @storybook/core 3.4.7

Affected platforms

• Webpack
• TypeScript

[Ailrun]

Resolved in #3785.

[swernerx]

Seems that there is some issue when dealing with "normal" "webpack.config.js". After updating I get this error:

WARN => Custom configuration file /Users/swerner/Workspace/init/display/node_modules/edge-storybook/lib/webpack.config.js is detected
WARN    but impossible to import loader for .js
INFO Using default webpack setup based on "create-react-app".

I overlooked this first as this does not throws (which it probably should do). Also I am wondering what it should do for configs which do not require transpilation.

The "interpret" package returns null for both .js and .json it seems. Which affects registerCompiler which returns 0 in this case which leads to this warning.

[Ailrun]

@swernerx Why do you think it should throw?

[swernerx]

I think it should throw because there might be unwanted side-effects if my very own config is not loaded. This has to be very explicit and visible to the user. Ignoring the issue somewhat by only raising a warning is IMHO not enough. Just falling back to some default is clearly not what the user expects when defining a custom webpack config.

But this is really another discussion. The bug right now is that actually two folded:

1. Should correctly handle .js configs like before without showing a warning.
2. Should output a warning or even throw when requiring the custom webpack config fails.

The second issue is about this code:

      try {
        return requireConfig(customConfigPath);
      } catch (e) {
        // do nothing
      }

We really shouldn't hide e.g. parse errors.

[Ailrun]

For 1., handling .js or .json is not that hard (since interpret package have null interpreter for them), and for 2., ye I think you're right. Could you make a PR? Nowdays I'm little busy because of work...

FYI, you can use permalink to link specific code like following (which gives a hyperlink to the file)
https://github.com/storybooks/storybook/blob/466b8dff9ec0b4d0e0d64df0fad8dc7b18bc3e48/lib/core/src/server/loadCustomWebpackConfig.js#L77-L81

[swernerx]

I'll do a PR. Will probably be done during the this week.

[pelotom]

So is loading a custom webpack.config.js just completely broken right now? Is there any workaround?

[Ailrun]

@pelotom It works well. It just displays annoying warning when you use .js extension for custom webpack config.

[sakulstra]

are you sure? I just tried upgrading from latest 3.x to 4.0.0-alpha.13 and it seems like at least webpack aliases defined in webpack.coonfig.js aren't loaded any more.

[pelotom]

One thing I discovered is that currently if webpack.config.js throws, the error is swallowed and it just silently uses the default config...

[Ailrun]

@pelotom Silently? I mean, at least it will displays Using default webpack setup based on "create-react-app" or something like that. If you mean "There is no displayed error" by "silently", yes, you are right, and of course displaying error is better and that's what @swernerx said in previous comment.

@sakulstra At least I tested it with my commercial project and storybook examples for .js file, and with my personal project for .ts file.

[pelotom]

@Ailrun

Silently? I mean, at least it will displays Using default webpack setup based on "create-react-app" or something like that. If you mean "There is no displayed error", yes, you are right, and of course that's better and that's what @swernerx said in previous comment.

I thought @swernerx' comment was about if you use an unsupported language extension for your webpack config... I'm talking about there being a thrown error inside your webpack config.

[Ailrun]

@pelotom See 2. of #3780 (comment), he mentioned about error emitted while requiring custom webpack config.

[pelotom]

@Ailrun I see, thanks

[sirtimbly]

Just to be clear: I believe custom webpack.config.js isn't even being loaded right now. I was able to get a custom webpack.config.js to work when I went back to alpha.10 (before this change went in) Do you have tests you can use to confirm custom webpack configs are actually being used?

[Ailrun]

@sirtimbly yes, I tested with the custom webpack files in the example. When custom on didn't load, it gave me an error.

[Ailrun]

Probably your webpack config have problem and errors are swallowed by that try-catch.

[1999]

I can't say that this message is very helpful: I'm trying to set up the webpack config, webpack.config.ts file exists but it obviously doesn't even get read and this message doesn't say anything about how to fix it.