WordPress gems for devs: Accessibility with HTML API

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

Event	Date	Branch	Links
IPC Munich 2025	29 October 2025	conf/IPCMunich2025	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()
  • set_attribute()
  • set_bookmark()
  • seek()
  • get_updated_html()
• WP_HTML_Processor
  • HTML_Serialization_Builder? 😱
  • WP_HTML_Search😱😱
• Block filters
  • render_block hook

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

• Accessibility development best practices
• HTML Tag Processor Roadmap
• Progress Report: HTML API
• Introducing the HTML API in WordPress 6.2
• HTML standards

Tools

• online check websiteaccessibilitychecker.com
• Chrome extension axe DevTools
• Chrome extension Funkify – Disability Simulator
• Chrome extension HeadingsMap
• Chrome extension WAVE Evaluation Tool

Equivalents in other PHP frameworks

None.