Add script and style REST APIs

[spacedmonkey]

Description

Create REST APIs for registered scripts and styles.

See original ticket at #48654

How has this been tested?

Endpoints can be found at
/__experimental/scripts and /__experimental/styles

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• My code has proper inline documentation.
• I've included developer documentation if appropriate.
• I've updated all React Native files affected by any refactorings/renamings in this PR.

[jorgefilipecosta]

cc: @StevenDufresne as I think this ticket may be important for the block directory work.

[StevenDufresne]

Noting:

In order to make use of this endpoint in the Block Directory Package, we will need to update the code to install then add scripts. It currently adds scripts and tries to install.

Coincidentally, I have a PR open that does exactly that : #20001.

[spacedmonkey]

Worth noting this is WIP. It has no tests and only enough comments and formatting that travis passes. It really needs someone from GB team to look and maybe use before we continue with more PHP work. I don't want to spend time on a none starter.

[noahtallen]

cc @ockham this relates to some stuff we've discussed related to more async loading of things in the editor

[azaozz]

As mentioned at #21684 (comment) I'm not sure how the REST API should be used together with core's Script Loader. Is the purpose to duplicate script loader in JS, or perhaps partially extend it, or..?

If the current Script Loader must be used, it seems a lot simpler to just add a function to it that will take a script's handle as param, run WP, calculate the dependencies, and return either the script tags (including inline scripts) or the concatenated JS as blob, or... anything else that may be useful. Of course that will need a list (array, CSV, etc.) of already loaded script handles that will be excluded from the calculated dependencies.

[spacedmonkey]

@azaozz This REST API allows you to pass a script and style handle and it return an array of javascript / css files. From that, a script / style tag could easily be generated in gutenberg.

As for concatting javascript / css files. Little worried about this that jQuery are react might be reloaded unnecessarily. Feel like returning the data is more useful.

[spacedmonkey]

Now that #21065 has been merge, I have updated the PR with embedded script and styles. Meaning that urls are for scripts can be requested as part of api request.

What you do think of this PR @TimothyBJacobs ?

[azaozz]

This REST API allows you to pass a script and style handle and it return an array of javascript / css files. From that, a script / style tag could easily be generated in gutenberg.

Right, but an array of URIs to javascript files doesn't include all of the dependencies. There are also the "inline" dependencies (the js code added with add_inline_script() and wp_localize_script()) that would be missing.

For example, wp-mediaelement has four dependencies, two are in <script> tags and two are in *.js files. When wp-mediaelement is enqueued in script-loader, the resulting HTML is something like:

<script>
var mejsL10n = {"language":"en","strings":{"mejs.download-file":"Download File", ... }};
</script>
<script src='/wp-includes/js/mediaelement/mediaelement-and-player.js?ver=4.2.13-9993131'></script>
<script src='/wp-includes/js/mediaelement/mediaelement-migrate.js?ver=5.5-alpha-20200526.094621'></script>
<script>
var _wpmejsSettings = {"pluginPath":"\/wp-includes\/js\/mediaelement\/","classPrefix":"mejs-","stretching":"responsive"};
</script>
<script src='/wp-includes/js/mediaelement/wp-mediaelement.js?ver=5.5-alpha-20200526.094621'></script>

As far as I see currently there is no support for the JS code that goes in the two <script> tags. Only the URIs that go in <script src="..."> tags are supported.

Looking at how the inline scripts can be supported, there are generally two methods:

• Each dependency could be an object that includes the before and after script code (when present). Then on the js side these chunks of js code will have to be run with eval().
• All of the dependencies can be gathered and concatenated on the server (using file_get_contents(), etc.) then returned as one big chunk of js code. (In order for this to work, the already loaded scripts will have to be excluded from the request, or a list of the already loaded scripts will have to be passed to the server, so they can be excluded there).

[spacedmonkey]

@azaozz Have you reviewed the output of the api?

Take this example from - /wp/v2/scripts/wp-ajax-response

{"handle":"wp-ajax-response","src":"\/wp-includes\/js\/wp-ajax-response.min.js","deps":["jquery"],"ver":false,"args":1,"extra":{"data":"var wpAjax = {\"noPerm\":\"Sorry, you are not allowed to do that.\",\"broken\":\"Something went wrong.\"};"},"textdomain":null,"translations_path":null,"url":"http:\/\/localhost:8889\/wp-includes\/js\/wp-ajax-response.min.js","_links":{"self":[{"href":"http:\/\/localhost:8889\/wp-json\/wp\/v2\/scripts\/wp-ajax-response"}],"collection":[{"href":"http:\/\/localhost:8889\/wp-json\/wp\/v2\/scripts"}],"deps":[{"href":"http:\/\/localhost:8889\/wp-json\/wp\/v2\/scripts\/?dependency=wp-ajax-response"}]}}

As you can see, the dependies are an listed as an array and all the extras are including, like translated strings.

This is all the data is required to rebuild the enqueue system in javascript.

[azaozz]

Have you reviewed the output of the api?

Hmmmm, don't see this here? Will reset caches/npm and try again, sorry.

[azaozz]

Got it to work, was my error, sorry :)

Couple of quick notes:

1. Testing with https://site.tld/wp-json/wp/v2/scripts/wp-mediaelement the result is as expected:

handle: "wp-mediaelement"
src: "/wp-includes/js/mediaelement/wp-mediaelement.js"
...
url: "https://site.tld/wp-includes/js/mediaelement/wp-mediaelement.js"

However testing with https://site.tld/wp-json/wp/v2/scripts/mediaelement (which has no src as it is dependencies-only handle), the results are:

handle: "mediaelement"
src: false
...
url: "/wp-json/wp/v2/scripts/mediaelement?ver=4.2.13-9993131"

Wondering why the discrepancy for the url (seems it has to be empty, perhaps, when no src)?

2. Testing with https://site.tld/wp-json/wp/v2/scripts/?dependency=wp-mediaelement (to get the handle plus all dependencies), the result is as expected.

There is a discrepancy with the extra depending on how the data was added (it's the same in PHP).

extra:
    data: "var _wpmejsSettings = ..."
handle: "mediaelement"

extra:
    before: Array(2)
        0: false
        1: "var mejsL10n = ..."
handle: "mediaelement-core"

Wondering if the API should be normalizing these in some way or at least removing the empty/invalid elements? On the server that data is not for "direct consumption", it's just a storage that shouldn't be accessed directly. Also note that plugins can add more data there, so an array is probably the proper format.

[azaozz]

Another thing that needs fixing is to perhaps run the init and wp_enqueue_scripts actions in the API. Many plugins use them to enqueue/dequeue scripts and/or add data, etc. Also, perhaps may be a good idea to have a specific action only for the API dependencies.

[youknowriad]

Thanks for your work here. I'm closing this PR now as we have import maps as an alternative now on Core.

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Co-authored-by: spacedmonkey <spacedmonkey@git.wordpress.org>
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Co-authored-by: dd32 <dd32@git.wordpress.org>
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