JavaScript Temporal PlainTime
Temporal.PlainTime Object Reference
The Temporal.PlainTime object is a time object with no date.
It represents an ISO 8601 wall-clock time without a date or time zone.
Example: 14:30:00.
New to JavaScript Temporal Dates?
Temporal.PlainTime Methods
Revised March 2026
| Constructing | Description |
|---|---|
| from() | Returns a new PlainTime object from another object or a string |
| Arithmetic | |
| add() | Returns a new PlainTime with a duration added |
| subtract() | Returns a new PlainTime with a duration subtracted |
| round() | Returns a new PlainTime rounded to a given unit |
| Comparing | |
| compare() | Returns -1, 0, or 1 from comparing two times |
| equals() | Returns true if two PlainTime objects are identical |
| since() | Returns the difference since another time |
| until() | Returns the difference until another time |
| Converting | |
| with() | Returns a new PlainTime with specified fields modified |
| Formatting | |
| toString() | Returns an RFC 9557 format string representation |
| toJSON() | Returns an RFC 9557 format string for JSON serialization |
| toLocaleString() | Returns a language-sensitive representation of the time |
| valueOf() | Throws a TypeError (prevents temporals from being converted to primitives) |
Temporal.PlainTime Properties
The Temporal.PlainTime object has 6 properties of time information.
| Property | Description |
|---|---|
| calendarID | Calendar system identifier ("iso8601") |
| day | The day as an integer (1-31) |
| dayOfWeek | The day of the week as an integer (1 = Monday) |
| dayOfYear | The ordinal day of the year |
| daysInMonth | The total number of days in that month |
| daysInWeek | The total number of days in that week |
| daysInYear | The total number of days in that year |
| era | The era name of the calendar, if applicable |
| eraYear | The year within the era, if applicable |
| inLeapYear | A boolean indicating if the year is a leap year |
| month | The month as an integer (1-12) |
| monthCode | A string code for the month ("M01") |
| monthsInYear | The total number of months in that year |
| weekOfYear | The week number within the year |
| year | The year as an integer |
| yearOfWeek | The year that the week belongs to |
Browser Support
Temporal is a major update to the JavaScript standard (TC39).
It is currently fully supported in Chrome, Edge, and Firefox, and is expected to reach full availability across browsers before the summer of 2026.
| Chrome 144 |
Edge 144 |
Firefox 139 |
Safari |
Opera |
| Jan 2026 | Jan 2026 | May 2025 | 🚫 | 🚫 |
Opera and Safari Support
Opera support will probably appear 1-3 browser cycles after Chromium, which often means a few months later.
The implementation is actively in development and can be tested today in Safari Technology Preview by enabling the --use-temporal runtime flag.
Polyfill
Until Opera and Safari supports Temporal natively, you can use the official polyfill:
<script
src="https://cdn.jsdelivr.net/npm/@js-temporal/polyfill/dist/index.umd.js">
</script>
