JavaScript PlainDate toJSON()
Example
const instant = Temporal.PlainDate.from("2026-05-17");
let text = instant.toJSON();
Try it Yourself »
Description
The toJSON() method returns a string representing the plain date
in RFC 9557 format.
The toJSON() method returns the same as the
toString() method.
The toJSON() method is intended to be called
by the JSON.stringify() method.
The toJSON() method does not change the original duration.
Syntax
plaindate.toJSON()
Parameters
| NONE |
Return Value
| Type | Description |
| String | The plaindate in RFC 9557 format. |
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>
