Add components for dropdown items

[janfaracik]

Background

Currently to create a dropdown in Jenkins you'd do something like:

<l:overflowButton text="My dropdown">
  <a class="jenkins-dropdown__item" href="my-url" rel="noopener noreferrer" target="_blank">
    <div class="jenkins-dropdown__item__icon">
      <l:icon src="symbol-external" />
    </div>
    ${%Website}
  </a>
</l:overflowButton>

The upside of this approach is that you're not restricted as to what you put in your dropdown, e.g. you can display an image or video in your dropdown if you so wish.

The downsides of this however:

• Inconsistencies can arise between how developers implement dropdowns
• There isn't currently an easy way of having submenus in dropdowns
• There's an inconsistency between how model-link dropdowns work (they're powered via JSON rather than Jelly)

My proposal would be to have a set of components, e.g. dd:item, dd:heading, dd:separator, to be a standardised way of implementing such dropdowns. The components themselves are just simple wrappers of template elements, which are converted via JS into HTML to be consumed by Tippy. This gives us the advantage that our implementations of dropdowns are standardised and that our JS API for dropdowns is consistent between Jelly dropdowns and model-link JSON dropdowns.

<template data-dropdown-type="ITEM"
          data-dropdown-id="${attrs.id}"
          data-dropdown-icon="${icon}"
          data-dropdown-text="${attrs.text}"
          data-dropdown-href="${attrs.href}"
/>

To allow for custom content in dropdowns I've added a dd:custom component which will display its child contents in the dropdown, its content needs to be escaped unlike the above components.

As part of this change to demonstrate submenus I've updated the dashboard/build history to use a dropdown, which has a submenu for RSS feeds.

Let me know your thoughts 👍

Testing done

• Tried existing dropdowns in Jenkins, all appear to work correctly
• Dashboard dropdown works, displays icon legend and submenu as expected
• There are no dropdown usages in plugins yet so now seems a good time to cement the API.

Proposed changelog entries

• Add components for dropdown items. Refer to the new Design Library Dropdowns page for implementation details.

Proposed upgrade guidelines

N/A

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Desired reviewers

@jenkinsci/sig-ux

Before the changes are marked as ready-for-merge:

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[mawinter69]

The overflowButton tag could also need more documentation

[mawinter69]

Another thing would be to be able to provide a url from where you can fetch json or a callback that can generate the html. That way you can dynamically update the menu without a page reload. As the dropdown js things are not exposed to plugins, I basically had to reimplement it in customizable header plugin, also creating my own webpack so I can access tippy.

[janfaracik]

Another thing would be to be able to provide a url from where you can fetch json or a callback that can generate the html. That way you can dynamically update the menu without a page reload. As the dropdown js things are not exposed to plugins, I basically had to reimplement it in customizable header plugin, also creating my own webpack so I can access tippy.

Definitely a good idea. There's the existing model-link stuff which could probably be extended to support that functionality.

[Kevin-CB]

Looks fine security wise

[timja]

All looks good, not tested locally, could you update the design library though please?

[NotMyFault]

Thanks!

[daniel-beck]

The custom tags look a lot better than the HTML, and a new taglib seems like a good location 👍

Re no changelog, this should have at least a Developer: entry.

[daniel-beck]

See previous review

[janfaracik]

Anybody have any other blockers with this PR or is it good to go?

[daniel-beck]

Should be xmlEscape'd (probably including the URL even though it's not new here).

obsolete

[timja]

/label ready-for-merge

---

This PR is now ready for merge, after ~24 hours, we will merge it if there's no negative feedback.

Thanks!

[basil]

Caused jenkinsci/pipeline-graph-view-plugin#391