JavaScript Temporal Duration round()
Example
const d1 = Temporal.Duration.from({ hours:2, minutes:30, seconds:10 });
const d2 = d1.round("hour");
Try it Yourself »
Description
The round() method returns a new duration with this duration rounded.
The round() method does not change the original duration.
Syntax
duration.round(unit)
Parameters
| Parameter | Description |
| unit | A string representing the smallest unit option. |
Return Value
| Type | Description |
| Object | A new duration object, where the largest unit is no larger than the largest unit option, and the smallest unit is no smaller than the smallest unit option. |
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>
