WordPress gems for devs: HTML API

Repository for code examples and resources used in the "WordPress gems for devs: HTML API" talk.

Event	Date	Branch	Links
WP Suomi 2025	10 October 2025	conf/WPSuomi2025	Event | Slides
IPC Berlin 2025	4 June 2025	conf/IPC-Berlin-2025	Event | Slides
WordPress Meetup Lisboa	15 May 2025	meetup/lisboa-0525	Event | Slides

HTML API

What problems does it solve?

It makes manipulating HTML faster, easier, and more controlled, making jQuery/JavaScript obsolete for many use cases.

It is built completely custom, starting with HTML standards, which means the parser is never surprised by the HTML it receives but rather it supports the HTML we will probably never see.

Interactivity API wouldn't be possible without it.

Reference

• WP_HTML_Tag_Processor
  • next_tag()
  • get_tag()
  • get_attribute()
  • remove_attribute()
  • get_updated_html()
• WP_HTML_Processor
  • HTML_Serialization_Builder? 😱
  • WP_HTML_Search😱😱

Examples

• Add and remove classes
• Set aspect ratio for an iframe.
• Test if images have size values set
• Add image size to image src
• Table of contents generator
• Tests:
  • HTML Tag Processor functionality
  • WP_HTML_Tag_Processor bookmark functionality

Resources

• HTML Tag Processor Roadmap
• Progress Report: HTML API
• Introducing the HTML API in WordPress 6.2
• HTML standards

Equivalents in other PHP frameworks

None.