Introduce wp_js_dataset_name() for custom data attributes.

[dmsnell]

Trac ticket: Core-61501
See: #6429

As part of opening up custom data attributes, it’s important for Core to know what is and what isn’t a custom data attribute. Further, it’s important to know what the translated name of a custom data attribute is when read via the JavaScript .dataset property.

This patch introduces two new functions to transform between these two representations. While this started as a one-way transform from custom attribute name to dataset property name, it became apparent that the reverse transform could be just as confusing in some cases as the forward transform. Therefore, a second function has been added to lower the risk of producing a mistaken custom data attribute.

---

With this patch, developers can call wp_html_custom_data_attribute_name( 'postId' ) to get the name of the proper HTML attribute name such that it will match the JS code, building correlations between the JS and PHP sources. In this case, it would return data-post-id.

More complicated cases make the relevance of having well-defined functions more obvious:

• data-test <> test
• data-1 <> 1
• data-😢-8 <> 😢-8
• data-one:more <> one:more
• data-CAPS <> caps (<> data-caps)
• DATA--UPPER-alreadY <> UpperAlready (<> data--upper-already)
• data---one---two--- <> -One--Two---
• data- <> ``

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[dmsnell]

@peterwilsoncc@westonruter do either of you have thoughts about the structure of this proposed new module? It serves the work opening up custom data attributes by providing the necessary functions to parse them.

But it introduces another module in the top-level of wp-includes too. I think there could be plenty of new JS-interop functions, and there are some Trac tickets open for such things, so I reasoned that it might make sense to collect them in one place.

[westonruter]

@dmsnell I love this.

In regards to where the functions should be located, to me it seems they may make sense being added to src/wp-includes/script-loader.php. There are other related functions in there.

[dmsnell]

@westonruter I like this idea, but once I started implementing it I started liking it less.

• script-loader is full of larger and more integrated functionality for generating HTML on the rendered page.
• it’s a huge module with over three thousand lines.

my idea with js-interop.php is that it could be full of relatively isolated and pure functions whose purpose is purely to translate between PHP and JavaScript.

I added your changes in bb63d3c, so I would like to know your thoughts after the change and if you think it’s worth the tradeoffs to group it in that existing file.

[dmsnell]

@westonruter I’m going to merge as-is, but I would really love some additional thought on this: if we leave it in script-loader.php then it’s not available until a lot of other modules such as post.php and temp†e.php. If those are only providing functions I guess it’s all the same, but I want to double-check that we aren’t inviting issues with calling these functions in theme code before it’s been loaded.

I expect the if we identify problems during the Beta period we can move these back into their own new module.

[dmsnell]

Merged in 16c66d7
[61007]