Temporal.ZonedDateTime.prototype.startOfDay()
Limited availability
This feature is not Baseline because it does not work in some of the most widely-used browsers.
Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.
The startOfDay()
method of Temporal.ZonedDateTime
instances returns a Temporal.ZonedDateTime
object representing the first instant of this date in the time zone. It usually has a time of 00:00:00
, but may be different if the midnight doesn't exist due to offset changes, in which case the first time that exists is returned.
It is equivalent to calling withPlainTime()
with no arguments.
Syntax
startOfDay()
Parameters
None.
Return value
A Temporal.ZonedDateTime
object with instant t
, such that:
- The date at
t
is different from the date one nanosecond beforet
. - The date at
t
is the same as the date ofthis
.
Examples
Using startOfDay()
// In the US, DST transitions happen at 2am, so the midnight exists
const dt = Temporal.ZonedDateTime.from(
"2024-03-10T12:00:00-04:00[America/New_York]",
);
console.log(dt.startOfDay().toString()); // "2024-03-10T00:00:00-05:00[America/New_York]"
// In Brazil, DST transitions happened at midnight, so the midnight didn't exist
const dt2 = Temporal.ZonedDateTime.from(
"2015-10-18T12:00-02:00[America/Sao_Paulo]",
);
console.log(dt2.startOfDay().toString()); // "2015-10-18T01:00:00-02:00[America/Sao_Paulo]"
Specifications
Specification |
---|
Temporal proposal # sec-temporal.zoneddatetime.prototype.startofday |
Browser compatibility
Report problems with this compatibility data on GitHubdesktop | mobile | server | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
startOfDay |
Legend
Tip: you can click/tap on a cell for more information.
- No support
- No support
- Experimental. Expect behavior to change in the future.
- See implementation notes.
- User must explicitly enable this feature.
See also
Temporal.ZonedDateTime
Temporal.ZonedDateTime.prototype.with()
Temporal.ZonedDateTime.prototype.add()
Temporal.ZonedDateTime.prototype.subtract()
Temporal.ZonedDateTime.prototype.hour
Temporal.ZonedDateTime.prototype.hoursInDay
Temporal.ZonedDateTime.prototype.timeZoneId
Temporal.ZonedDateTime.prototype.getTimeZoneTransition()