JavaScript Instant since()
Example
const start = Temporal.Instant.from("2026-05-16T14:30:00Z");
const end = Temporal.Instant.from("2026-05-17T14:30:00Z");
const duration = end.since(start, {smallestUnit:"hours"});
Try it Yourself »
Description
The since() method returns a duration object representing
the duration from another instant.
The since() method does not change the original instant.
Syntax
instant.since(other)
Parameters
| Parameter | Description |
| other | Another instant. |
Return Value
| Type | Description |
| Object | A duration object representing the duration since the other instant. |
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 Support
Opera support will probably appear 1-3 browser cycles after Chromium, which often means a few months later.
Safari Support
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.
Example
<script
src="https://cdn.jsdelivr.net/npm/@js-temporal/polyfill/dist/index.umd.js">
</script>
<script>
// Now you can use Temporal
const today = Temporal.Now.plainDateISO();
</script>
