Hey Mathias,
On 3/31/23 5:56 AM, Mathias Bynens wrote:
Contact emails
math...@chromium.org
Specification
https://github.com/whatwg/html/pull/7908
<https://github.com/whatwg/html/pull/7908>
Summary
The <input pattern>attribute allows developers to specify a regular
expression pattern against which the input’s values are checked for
validity.
<label>
Part number:
<inputpattern="[0-9][A-Z]{3}" name="part"
title="A part number is a digit followed by three uppercase
letters.">
</label>
When the patternattribute was first implemented, these regular
expressions were compiled without any RegExp flags. In 2014, the HTML
Standard changed this by implicitly enabling the uflag for the pattern
attribute, enabling better Unicode support (including support for
Unicode character properties like \p{Letter}). This change shipped in
Chrome 53. <https://chromestatus.com/feature/4753420745441280>
Now, we’re taking this to the next level by enabling the new RegExp
vflag <https://v8.dev/features/regexp-v-flag>instead of u, enabling
the use of set notation, string literal syntax, and Unicode properties
of strings.
(Context: The RegExp vflag is a JavaScript language feature which
previously went through the Blink Intents process and shipped in
Chrome 112 <https://chromestatus.com/feature/5144156542861312>. This
new ChromeStatus entry is specifically about integrating it with the
HTML patternattribute.)
Blink component
Blink>Forms
<https://bugs.chromium.org/p/chromium/issues/list?q=component:Blink%3EForms>
Search tags
unicode <https://chromestatus.com/features#tags:unicode>, regexp
<https://chromestatus.com/features#tags:regexp>, pattern
<https://chromestatus.com/features#tags:pattern>, validation
<https://chromestatus.com/features#tags:validation>
TAG review
TAG review status
Not applicable
Risks
Interoperability and Compatibility
The spec patch athttps://github.com/whatwg/html/pull/7908
<https://github.com/whatwg/html/pull/7908>lists the potentially
breaking changes. Some patterns that previously would compile, now
throw an early error with the vflag — specifically those with a
character class including either an unescaped special character or a
double punctuator.
We expect such patterns to be rare. To validate this assumption we’ve
added a UseCountercalled
HTMLPatternRegExpUnicodeSetIncompatibilitiesWithUnicodeMode
<https://chromestatus.com/metrics/feature/popularity#HTMLPatternRegExpUnicodeSetIncompatibilitiesWithUnicodeMode>in
M112, which tracks patterns in any JavaScript uRegExps generated via
the HTML patternattribute that would throw if they were used with the
vflag.
Importantly, note that any throwing pattern gracefully degrades — it
simply behaves as if the patternattribute wasn’t present, resulting in
inputElement.validity.valid === truefor any input value. Consequently,
the only compatibility risk is that some value/pattern combinations
that would previously result in inputElement.validity.validbeing
falsenow result in it being true. Thus, for every UseCounterhit, it
could still be that there is no actual breakage — the UseCounterjust
gives us the upper bound.The currently available data from Beta
suggests the UseCounterhits for 0.0393% of Chrome page loads.
I'm somewhat curious to see how much that UseCounter will grow (if at
all) when 112 goes to stable next week...
Do you have any concerns about certain inputs being sent to a server
that might not have any backend validation, that would previously be
prevented by the u-vintage validation?
Gecko: Positive (Mozilla standards position request
<https://github.com/mozilla/standards-positions/issues/745>,
implementation tracking issue
<https://bugzilla.mozilla.org/show_bug.cgi?id=pattern-v>)
WebKit: Positive (WebKit standards position request
<https://github.com/WebKit/standards-positions/issues/132>,
implementation tracking issue
<https://bugs.webkit.org/show_bug.cgi?id=pattern-v>)
Web developers: No signals
Other signals:
Debuggability
The patternattribute is already well-supported in DevTools and other
tooling; no changes are necessary.
Will this feature be supported on all six Blink platforms
(Windows, Mac, Linux, Chrome OS, 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>?
Pull Request: https://github.com/web-platform-tests/wpt/pull/38547
<https://github.com/web-platform-tests/wpt/pull/38547>
Flag name
N/A
Requires code in //chrome?
False
Tracking bug
https://bugs.chromium.org/p/chromium/issues/detail?id=1412729
<https://bugs.chromium.org/p/chromium/issues/detail?id=1412729>
Sample links
https://mathiasbynens.be/demo/pattern-u-vs-v
<https://mathiasbynens.be/demo/pattern-u-vs-v>
Estimated milestones
M114
Link to entry on the Chrome Platform Status
https://chromestatus.com/feature/5149507107422208
<https://chromestatus.com/feature/5149507107422208>
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