Chore: upgrade dependencies of browser test

[g-plane]

Prerequisites checklist

• I have read the contributing guidelines.

What is the purpose of this pull request? (put an "X" next to an item)

[x] Other, please explain: upgrade dependencies

What changes did you make? (Give an overview)

Upgrade dependencies of browser test, such as Karma and webpack.

Is there anything you'd like reviewers to focus on?

No.

[mdjermanovic]

I think we should clarify the purpose of this build and browser tests in the eslint/eslint repository.

Is it just to ensure, as far as it's possible, that the online demo will work after the release? If so, should we always have the same Webpack version and configuration here as in the eslint/website repo, since the online demo now has a completely separate build process.

[g-plane]

We don't need to keep the same webpack version and configuration with eslint/website, even don't need to use same bundler, because the built ESLint (in built/eslint.js) is a UMD module which can work independently.

[mdjermanovic]

We don't need to keep the same webpack version and configuration with eslint/website, even don't need to use same bundler, because the built ESLint (in built/eslint.js) is a UMD module which can work independently.

Yes, but then why are we producing build/eslint.js? I believe it doesn't get published on npm or used on our website.

I thought since we made a separate demo build in eslint/website that the only purpose of keeping build/eslint.js and browser tests in eslint/eslint is to get early errors if our demo would fail after the release (as stated in #12676), and for that purpose it would probably make more sense to have build processes as similar as possible.

[mdjermanovic]

To clarify, as of eslint/archive-website#665 and #12676, build/eslint.js isn't getting copied to the website repo.

Instead, website installs latest eslint from npm as a dependency, and then makes the demo bundle. Demo imports linter from node_modules, so all the bundling of ESLint is processed there.

[g-plane]

So, can we also upgrade webpack for eslint/website?

[mdjermanovic]

So, can we also upgrade webpack for eslint/website?

I think it makes sense to upgrade to webpack 5. It looks like webpack 4 is still maintained, but it most likely won't last forever.

We should probably finish the website PR first, and then if everything seems to be working sync the changes here,

[mdjermanovic]

Since we are now bundling build/eslint.js into tests, do we need to load it in the browser (i.e. can we remove it from the files array above)?

[g-plane]

Are there any pros?

[mdjermanovic]

Technically not much if any, but for a better understanding of what's happening here, so that someone who reads the code doesn't have to think about why are we loading the script and where is it used (while it actually isn't used, the code is bundled in another script). Is there a benefit of loading build/eslint.js now?

[mdjermanovic]

LGTM, thanks! Good idea to remove compatRequire, I think this is now more similar to our actual eslint/website build.

[aladdin-add]

LGTM, but a small question, and surely it's not a blocker! :)

[aladdin-add]

is the config any difference with ./webpack.config.js? if no, we can just import it here:

webpack: require("./webpack.config.js"),

[g-plane]

The webpack configuration in root is for building ESLint as a library, while in Karma, it's for browser testing as an application.