Has this already run in canary and beta? If so, did it give any
indication of risk?
/Daniel
On 2026-04-01 16:30, Mike Taylor wrote:
Is there any fuzzing test coverage for this proposed change?
On 3/31/26 7:34 a.m., Chromestatus wrote:
*Contact emails*
[email protected], [email protected]
*Explainer*
https://github.com/WICG/declarative-partial-updates/blob/main/patching-explainer.md#proposed-markup
*Specification*
https://github.com/whatwg/html/pull/12118
*Summary*
Processing instructions (syntax: <?target data>) are an existing DOM
construct, exposed in XML, that allows node objects that are not
elements but can have some semantic meaning for the processing of a
document. For example, they can be used to denote ranges for
streaming or highlighting without requiring new DOM elements and
changing the DOM structure as far as CSS is concerned, or as
directives for the HTML parser about how to buffer and stream.
*Blink component*
Blink>HTML>Parser
<https://issues.chromium.org/issues?q=customfield1222907:%22Blink%3EHTML%3EParser%22>
*Web Feature ID*
html <https://webstatus.dev/features/html>
*TAG review*
https://github.com/w3ctag/design-reviews/issues/1134
*TAG review status*
Pending
*Goals for experimentation*
Changing the parser behavior to recognize processing instructions
might uncover web compatibility issues in certain websites (though
hopefully not!). We want to uncover them early in case it affects the
shape of the API. Note that this is a finch (to 1% stable) rather
than an OT.
*Risks*
*Interoperability and Compatibility*
This feature changes the HTML parser to recognize XML processing
instruction syntax, which was previously parsed as (bogus) comments.
Querying HA showed that this is relatively safe, specifically as it
doesn't parse xml-stylesheet and special characters like $.
/Gecko/: No
signal (https://github.com/mozilla/standards-positions/issues/1369)
/WebKit/: No
signal (https://github.com/WebKit/standards-positions/issues/628)
/Web developers/: No signals
/Other signals/:
*WebView application risks*
Does this intent deprecate or change behavior of existing APIs, such
that it has potentially high risk for Android WebView-based
applications?
/No information provided/
*Ongoing technical constraints*
None
*Debuggability*
/No information provided/
*Will this feature be supported on all six Blink platforms (Windows,
Mac, Linux, ChromeOS, Android, and Android WebView)?*
Yes
*Is this feature fully tested by web-platform-tests
<https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md>?*
Yes
https://wpt.fyi/results/html/syntax/parsing/parse-processing-instruction.tentative.html?label=master&label=experimental&aligned&q=processing-instruction
<https://wpt.fyi/results/html/syntax/parsing/parse-processing-instruction.tentative.html?label=master&label=experimental&aligned&q=processing-instruction>
*Flag name on about://flags*
/No information provided/
*Finch feature name*
HTMLProcessingInstruction
*Requires code in //chrome?*
False
*Tracking bug*
https://issues.chromium.org/issues/481087638
*Estimated milestones*
Shipping on desktop 150
Origin trial desktop first 148
Origin trial desktop last 150
Shipping on Android 150
Origin trial Android first 148
Origin trial Android last 150
Shipping on WebView 150
Origin trial WebView first 148
Origin trial WebView last 150
*Link to entry on the Chrome Platform Status*
https://chromestatus.com/feature/6534495085920256?gate=5414789998313472
*Links to previous Intent discussions*
Intent to Prototype:
https://groups.google.com/a/chromium.org/d/msgid/blink-dev/6981ee47.050a0220.baa59.0100.GAE%40google.com
This intent message was generated by Chrome Platform Status
<https://chromestatus.com>.
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