1513890 - Remove 'x-moz-errormessage' attribute

Status: RESOLVED FIXED

(Core :: DOM: Core & HTML, enhancement, P2)

Description

[Andrea Marchesini [:baku]]

x-moz-errormessage attribute can be used to have a custom error message when validating a form field. This is a mozilla-only attribute which was rejected in 2010 by w3: https://www.w3.org/Bugs/Public/show_bug.cgi?id=10923

Currently, a similar message can be set using setCustomValidity() method: https://html.spec.whatwg.org/#dom-cva-setcustomvalidity

This bug is about removing the support for this attribute.

Comment 1

[Olli Pettay [:smaug][[e-mail]]]

There are web pages hinting about this attribute, some pages say that title attribute would work the same way in some browsers. Better to verify how title attribute works elsewhere.

Comment 2

[Matthew N. [:MattN]]

Hmm… I could have used this recently for Web Payments UI if I had known about it.

(In reply to Olli Pettay [:smaug] (high review load) from comment #1)
> There are web pages hinting about this attribute, some pages say that title
> attribute would work the same way in some browsers. Better to verify how
> title attribute works elsewhere.

It sounds like Blink used to use @title to override the custom message but stopped doing so years ago.

We currently only use @title with @pattern and a problem is that we append our own string[1] to the @title but that's often not ideal. For example, UX wanted us to show the message "Enter a valid ZIP code for the country or region" but if we did:
> <input pattern="[0-9]{5}" title="Enter a valid ZIP code for the country or region">
leads to
> Please match the requested format: Enter a valid ZIP code for the country or region
which isn't great.

In our case we were already using `setCustomValidity` for another class of errors and it would have been a lot of work to re-implement @pattern and the other constraint attributes with `setCustomValidity` just to handle changing the message to remove the "Please match the requested format: " prefix.

For complicated forms it seems like a way to override the message shown while invalid without actually marking the field as invalid, like x-moz-errormessage, is still useful.

[1] https://dxr.mozilla.org/mozilla-central/rev/c2593a3058afdfeaac5c990e18794ee8257afe99/dom/locales/en-US/chrome/dom/dom.properties#45-46

Comment 3

[Andrea Marchesini [:baku]]

Attachment: validation.patch

Comment 4

[Edgar Chen [:edgar]]

Comment on attachment 9031373 [details] [diff] [review]
validation.patch

Review of attachment 9031373 [details] [diff] [review]:
-----------------------------------------------------------------

Looks good to me.

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/6533f8297b30
Get rid of x-moz-errormessage attribute, r=edgar

Comment 6

[Cristian Brindusan [:cbrindusan]]

https://hg.mozilla.org/mozilla-central/rev/6533f8297b30

Comment 7

[Kohei Yoshino [:kohei]]

Posted site compatibility note: https://www.fxsitecompat.com/en-CA/docs/2018/x-moz-errormessage-attribute-is-no-longer-supported/

Comment 8

[Chris Mills [:cmills]]

I've documented this:

mentioned that the attribute is removed in 66, and added an example of what you should do instead, to
https://developer.mozilla.org/en-US/docs/Web/HTML/Element/input#Custom_error_messages

Removed any mention of the attribute from
https://developer.mozilla.org/en-US/docs/Web/Guide/HTML/HTML5/Constraint_validation

Added compat data:
https://github.com/mdn/browser-compat-data/pull/3364

Added a note to the Fx66 rel notes:
https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Releases/66#HTML

Let me know if that's OK, thanks!