JS Package: Add Critical CSS Gen

[dilirity]

Fixes https://github.com/Automattic/boost-cloud/issues/267

Proposed changes:

• Add critical css gen package to the monorepo:
  • Browser build is now in build-browser (was dist before);
  • Node build is now in build-node (was lib before);
• Update browser version to not include playwright/puppeteer code;
• Update node version to not include iframe code;
• Update Boost to use the new package instead of the external repo. This will be done in a follow-up PR.

Other information:

• Have you written new tests for your changes, if applicable?
• Have you checked the E2E test CI results, and verified that your changes do not break them?
• Have you tested your changes on WordPress.com, if applicable (if so, you'll see a generated comment below with a script to run)?

Jetpack product discussion

n/a

Does this pull request change what data or activity we track or use?

no

Testing instructions:

Pre-requisites

• Go to the root of the js package;
• Run pnpm install;
• Build the package using pnpm build;
• There should be no errors.

Testing with the Boost plugin

• Apply the changes from this commit 3f586d8 (in reverse, the "removed" changes is what you need to add back to Boost);
• Setup free Boost;
• Install Boost dependencies using jetpack install plugins/boost;
• Build Boost using jetpack build plugins/boost;
• Try to generate critical css and make sure it's working.

[github-actions]

Are you an Automattician? Please test your changes on all WordPress.com environments to help mitigate accidental explosions.

• To test on WoA, go to the Plugins menu on a WordPress.com Simple site. Click on the "Upload" button and follow the upgrade flow to be able to upload, install, and activate the Jetpack Beta plugin. Once the plugin is active, go to Jetpack > Jetpack Beta, select your plugin, and enable the add/js-package/critical-css-gen branch.

  • For jetpack-mu-wpcom changes, also add define( 'JETPACK_MU_WPCOM_LOAD_VIA_BETA_PLUGIN', true ); to your wp-config.php file.

• To test on Simple, run the following command on your sandbox:

  bin/jetpack-downloader test jetpack add/js-package/critical-css-gen
  

  bin/jetpack-downloader test jetpack-mu-wpcom-plugin add/js-package/critical-css-gen
  

Interested in more tips and information?

• In your local development environment, use the jetpack rsync command to sync your changes to a WoA dev blog.
• Read more about our development workflow here: PCYsg-eg0-p2
• Figure out when your changes will be shipped to customers here: PCYsg-eg5-p2

[github-actions]

Thank you for your PR!

When contributing to Jetpack, we have a few suggestions that can help us test and review your patch:

• ✅ Include a description of your PR changes.
  
• ✅ Add a "[Status]" label (In Progress, Needs Team Review, ...).
  
• ✅ Add testing instructions.
  
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• ✅ Add changelog entries to affected projects
  

This comment will be updated as you work on your PR and make changes. If you think that some of those checks are not needed for your PR, please explain why you think so. Thanks for cooperation 🤖

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---

Boost plugin:

• Next scheduled release: none scheduled.

If you have any questions about the release process, please ask in the #jetpack-releases channel on Slack.

[pyronaur]

Followed the instructions and got this:

[anomiex]

Ah, it's not as bad as I thought since it's only importing types. Still, try this:

1. Fix the .gitattributes as mentioned in the other comment.
2. Download the build artifact from this PR, and unpack it to something like /tmp/jetpack-build.
   • Or, from a fresh checkout, do pnpm install && jetpack build --for-mirrors=/tmp/jetpack-build js-packages/critical-css-gen.
3. Create package.json with these contents:

   {
     "dependencies": {
       "@automattic/jetpack-critical-css-gen": "file:/tmp/jetpack-build/Automattic/jetpack-critical-css-gen",
       "typescript": "^5.5.4"
     }
   }

4. Create index.ts with these contents:

   import { generateCriticalCSS } from '@automattic/jetpack-critical-css-gen';
   
   console.log( 'The function is:', generateCriticalCSS );

5. Run npm install && npm exec tsc index.ts.

You'll get an error like

../jetpack-build/Automattic/jetpack-critical-css-gen/lib/browser-interface-playwright.d.ts:1:38 - error TS2307: Cannot find module 'playwright-core' or its corresponding type declarations.

1 import { BrowserContext, Page } from 'playwright-core';
                                       ~~~~~~~~~~~~~~~~~


Found 1 error in ../jetpack-build/Automattic/jetpack-critical-css-gen/lib/browser-interface-playwright.d.ts:1

Unfortunately, it looks like using an optional (peer) dependency to account for this case is complicated.

• Seems like the most straightforward way would be to have a separate entry point for BrowserInterfacePlaywright so people can do like import { BrowserInterfacePlaywright } from '@automattic/jetpack-critical-css-gen/playwright'; if they need it, rather than including it in the default entry point.
• Second way would be to get tsc to include a // @ts-ignore comment before the import line when it outputs lib/browser-interface-playwright.d.ts. By default it seems to strip those, not sure how to best configure it not to.

[haqadn]

One small thing and I think it's ready to get merged.

[haqadn]

LGTM!