The state of components, follow the browser language or the node's language?

[xfq]

Currently, it's not possible to specify the format of the numbers, and whether the numbers are half-width or full-width for the HTML <input type="date"> element. It seems to be bound to the browser's language preference. This will cause a problem: the internationalization status of the date component is separated from the internationalization status of the whole page.

Do we need a best practice about this (maybe in section 10)? For example:

• use the page/node's language by default, and if the browser's built-in date picker (or another component) does not support the page/node's language, fall back to the browser language
• use the browser language by default, but let the author override/control the appearance and localization of the component

[xfq]

HTML spec text: https://html.spec.whatwg.org/multipage/input.html#input-impl-notes

Related issues:

• https://www.w3.org/Bugs/Public/show_bug.cgi?id=17859
• Strengthen form control localization requirements whatwg/html#10812