> Typically all JS Dependencies are foreign and won’t be passed through :advanced and thus require Externs. > from https://shadow-cljs.github.io/docs/UsersGuide.html#externs Does that mean Closure Compiler not doing dead code elimination on the dependency library?

yes, if by dependency library you mean npm JS dependency.

I've been updating dependencies in a project and running into Module not provided: @babel/runtime/helpers/interopRequireDefault often. Tricky that it doesn't list which npm package / file is to blame. I think it has to do with using either @babel/runtime @babel/preset-react @babel/preset-env to pre-compile. Is it perhaps because I didn't configure .babelrc properly? I do have a babel.config.json that I think shadow-cljs uses.

@bbss kinda hard to say. why do you configure babel at all?

I've needed it several times when shadow couldn't compile when requiring an npm dep.

In this case it couldn't compile: https://github.com/dmonad/isomorphic.js/blob/main/browser.mjs

why not?

EOF when reading it IIRC

[2022-09-05 17:14:53.607 - WARNING] :shadow.build.babel/babel-transform-ex - {:code "/* eslint-env browser */\nexport const performance = typeof window === 'undefined' ? null : (typeof window.performance !== 'undefined' && window.performance) || null\n\nconst isoCrypto = typeof crypto === 'undefined' ? null : crypto\n\n/**\n * @type {function(number):ArrayBuffer}\n */\nexport const cryptoRandomBuffer = isoCrypto !== null\n  ? len => {\n    // browser\n    const buf = new ArrayBuffer(len)\n    const arr = new Uint8Array(buf)\n    isoCrypto.getRandomValues(arr)\n    return buf\n  }\n  : len => {\n    // polyfill\n    const buf = new ArrayBuffer(len)\n    const arr = new Uint8Array(buf)\n    for (let i = 0; i < len; i++) {\n      arr[i] = Math.ceil((Math.random() * 0xFFFFFFFF) >>> 0)\n    }\n    return buf\n  }\n", :file "/Users/baruchberger/nexus-core/node_modules/isomorphic.js/browser.mjs", :preset-config {:targets {"chrome" "90"}}, :shadow.build.babel/reply-to #object[clojure.core.async.impl.channels.ManyToManyChannel 0x2d46eb58 "clojure.core.async.impl.channels.ManyToManyChannel@2d46eb58"]}
RuntimeException EOF while reading

weird

I've also hit it on @material-ui v4

this isomorphic.js thing is a dependency of y-webrtc which is you'd use with yjs a pretty cool lookin' crdt lib.

instead of messing with babel you should probably just be using webpack instead

as described here https://code.thheller.com/blog/shadow-cljs/2020/05/08/how-about-webpack-now.html#option-2-js-provider-external

okay, cool didn't consider that. I'll check it out! Thanks 🙂

dunno what this error is. just seems to be missing a } at the end?

hmm no wait it doesn't

you definitely shouldn't have a babel config or manually call babel on the output or input. that is not expected to work

it also compiles fine on my machine

so maybe the babel config is causing it in the first place?

okay, that's a bit confusing to me in how far shadow-cljs will go there, there is some mention of manually passing things through babel, and that has worked out for me in the past. So just a .babelrc is supported, and I should get rid of the babel.config.json in my root?

Perhaps, let me check.

I don't know. what do you use them for? shadow-cljs ONLY uses babel to transform npm ESM code to commonjs. nothing else, not for polyfilling or whatever else

so if you make it do more you will essentially brick it

I wouldn't use babel for this at all but unfortunately the closure compiler is rather picky about its input, so I kinda have to

I use them because I thought it was needed to get some npm deps to work, here and there I've run into these babel-transform-ex.

no, you should not have any babel config whatsoever. unless you actually use babel manually anywhere I guess

but not for the babel used by shadow-cljs

Great, the babel.config.json seemed to be the problem, code now runs. Thank you very much!

On the topic of the babel config and closure compiler, I’m running into an ES6 transpilation of 'Public class fields' is not yet implemented. from the closure compiler and was trying to get shadow’s babel config to use include @babel/plugin-proposal-class-properties, but it doesn’t seem to. Is this a bad idea?

yes, that is bad. it is not a supported use case. basically if you need to use code that the closure compiler doesn't support you are better off using webpack

Hey! Anyone seen any videos or “for-dummies” material on externs?

do you not get any inference warnings?