content Clarify how to format a datetime-local value

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Clarify how to format a datetime-local value

Open nharper opened this issue 2 years ago • 1 comments

Summary

Motivation

The existing language suggests that one can take a Date object, call toISOString() on it, and use the resulting string as the value for a datetime-local input. This doesn't work, because toISOString() includes a "Z" at the end to indicate the timezone, while datetime-local expects the value to have no time-zone offset information.

Supporting details

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/toISOString describes the behavior of toISOString returning a value ending in Z. https://html.spec.whatwg.org/dev/input.html#local-date-and-time-state-(type=datetime-local) defines how datetime-local works and specifies that the value (if not empty) must be a valid local date and time string, which doesn't include timezone information (https://html.spec.whatwg.org/dev/common-microsyntaxes.html#valid-local-date-and-time-string defines "valid local date and time string").