Process attachments (CSS/JS) for HTMX responses and add drupal asset libraries

I have this working with in integration test. If anyone wants to see that locally, there is an asset-tests branch in the fork, which is this issue, plus the htmx dependency issue merged into the core 11.x branch. That allows the test to run. I'll bring that test over to this branch once the htmx dependency work is merged.

Blocker is in.

I hav two questions about merging drupalSettings.

ajax.js uses jQuery to merge the incoming drupalSettings value using the deep variation of .extend()

      if (response.merge) {
        $.extend(true, drupalSettings, response.settings);
      } else {
        ajax.settings = response.settings;
      }

In my contrib implementation I didn't want to start with a reliance on jQuery so adapted code from https://youmightnotneedjquery.com. I've kept this pattern in the MR at the moment, but I see that jQuery.extend() is used nearly a dozen other scripts. What's the best way forward? I see #3179551: Provide no-library equivalents of common/useful jQuery functions → but it doesn't include .extend().

2. The ajax API provides two options for drupalSettings above. I currently simply merge. What is the use case for not merging incoming settings?

I've added a Nightwatch test, and all Nightwatch tests are passing.

Thanks for the MR!

Glad to see this moving fast. Had a bunch of comment on the MR. Generally looks like things will work out :)

Thinking about the feedback on an additional processor service I realized that we should be able to simplify that whole part of the solution by adding some appropriate conditions to the existing HtmlResponseAttachmentsProcessor. I'm hitting a wrinkle though which is that HtmlResponseAttachmentsProcessor gets called more than once preparing the response to my test page. This is an issue because if I call setAlreadyLoadedLibraries on the assets, then they stop getting added in subsequent runs.

fathershawn → changed the visibility of the branch asset-tests to hidden.

fathershawn → changed the visibility of the branch 3521173-process-attachments-cssjs to hidden.

fathershawn → changed the visibility of the branch without-htmx-attachement-processor to hidden.

fathershawn → closed merge request !11944

Simplified as much as I could, seems to work as expected.

@nod_ requested two additional test cases in the prior PR.

1. htmx powered elements inserted by our legacy ajax
2. verify that our attach and detach behavior methods fire

I've added a route to the test_htmx module (/htmx-test-attachments/ajax) that creates markup for this test. In manual testing, htmx is inserted but does not process the inserted content. I think we need some glue code that calls htmx.process on markup inserted by our Ajax API.

The only way I see to verify that methods are called in the Nightwatch test is to use the callTracker assertion but this is deprecated, so I'm wondering if someone has a better approach?

I also added some documentation links to the JS files.

The Needs Review Queue Bot → tested this issue. It fails the Drupal core commit checks. Therefore, this issue status is now "Needs work".

This does not mean that the patch necessarily needs to be re-rolled or the MR rebased. Read the Issue Summary, the issue tags and the latest discussion here to determine what needs to be done.

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PHP 8.4 test failed

All tests passed

Nice simple solution @nod_. All tests green including the the added Ajax interaction test. What else do we need to move to RTBC?

Still open comments on the MR, those need adressing. :)

I can't mark the MR comment resolved but I removed the version requirement from the info.yml file in the test module.

All other unresolved MR comments are from the previous MR which we have closed.

Gonna go ahead and mark this RTBC so we can continue to move the HTMX proposal forward; given that this is currently experimental in core if we have to make any API changes or fixes then we should still be safe. Although it could do with another review from someone who writes more JavaScript than I do, I found the MR easy to follow and everything in it makes sense to me.

Also discussed this with @nod_ who pointed out that while we added the HTMX library already, it's not really much use without these changes - behaviors and assets are critical to integrating with the rest of Drupal's frontend - so tagging as an 11.2 release priority to allow others to start actually looking at how they might want to use this.