Declarative Partial Updates

Declarative fragments

Summary: An active <template> has for, src, or both. for="name" patches a processing-instruction marker. An empty for inserts in place, then the template is removed. src fetches a fragment. buffer inserts it in one shot instead of streaming. External includes are sanitized unless sanitize="unsafe". Inline templates are unsafe unless sanitize is set.

Explainer: fragment-include-explainer.md

Intent: Intent to Prototype: Declarative fragments

Chrome Platform Status: Declarative fragments

Proposal: Client side include · whatwg/html#2791

Tracking bug: 535664974

Behind chrome://flags/#enable-experimental-web-platform-features. A targeted inline <template for="name"> is the shipped out-of-order streaming behavior and can pass here even when src, buffer, and sanitize do not. Without the fragments prototype, <template for="name" src> is an empty patch: it clears the marker and does not fetch.

=== This is a demo of declarative fragments. ===

• in-place <template for>
• in-place <template for buffer>
• targeted inline <template for="name">
• targeted <template for src>
• in-place <template src for>
• buffered <template src buffer>
• external include is sanitized by default
• sanitize="unsafe" runs the fragment script
• inline sanitize strips the script
• src patch inside <table>