Harden/modernize JS in WP_Customize_Manager::remove_frameless_preview_messenger_channel()

[westonruter]

As pointed out by @dmsnell a ​PR comment for #58664, the JS logic in WP_Customize_Manager::remove_frameless_preview_messenger_channel() can be hardened/modernized. We can leverage URLSearchParams as well as URL rather than hacking with document.createElement('a'). This is similar to what was done for wp-embed in r56383.

[binsaifullah]

yes, it can be done, I think so.

Hardens/modernizes the JavaScript in WP_Customize_Manager::remove_frameless_preview_messenger_channel(), leveraging URL instead of document.createElement('a').

Trac ticket: https://core.trac.wordpress.org/ticket/59480

[nicolefurlan]

Testing Instructions

1. On /wp-admin/themes.php, live preview a theme that does not use full site editing (Twenty Twenty-One or older) by clicking "Live Preview" on one of the themes.
2. On /wp-admin/customize.php, open up dev tools and inspect the DOM to find the iframe within #customize-preview.
3. Open the URL in the data-src attribute in a new tab.
4. Verify that the customize_messenger_channel URL parameter is removed, and that the admin bar is shown.

[westonruter]

@nicolefurlan Thank you for the patch! FYI: No need to attach a patch as you can see the GitHub PR is automatically linked above. I'll review your PR.

[nicolefurlan]

Replying to westonruter:

@nicolefurlan Thank you for the patch! FYI: No need to attach a patch as you can see the GitHub PR is automatically linked above. I'll review your PR.

Thank you! That's good to know. This was my first core contribution so I wasn't totally sure :)

[nicolefurlan]

Patch for #59480

[nicolefurlan]

@westonruter I did update the patch in this ticket to reflect the changes we discussed in the PR, just to make sure things stay consistent. But going forward, I won't bother adding a patch. 👍

[westonruter]

In 56749:

Customize: Harden and modernize URL manipulation in WP_Customize_Manager::remove_frameless_preview_messenger_channel().

Since IE11 is no longer supported, the URL and URLSearchParams APIs can now be leveraged for simpler and more robust URL manipulation. This was done similarly in [56383] for embed.js.

Props nicolefurlan, dmsnell, westonruter.
Fixes #59480.

Committed in r56749. Congratulations on your first core contribution!

[webcommsat]

@westonruter as this ticket is closed as a fix, does it still needs its other keywords listed, eg good first bug, needs testing etc? I am just going through tickets in the milestone by component to re-check for the Field Guide and Dev notes, and came across this. Thanks.

[westonruter]

Replying to webcommsat:

@westonruter as this ticket is closed as a fix, does it still needs its other keywords listed, eg good first bug, needs testing etc? I am just going through tickets in the milestone by component to re-check for the Field Guide and Dev notes, and came across this. Thanks.

I removed good-first-bug and needs-testing.