PlainMonthDay toJSON()
Example
// Create a PlainMonthDay object
const date = Temporal.PlainMonthDay.from("05-17");
// Format to JSON
let text = date.toJSON();
Try it Yourself »
Description
The toJSON() method returns a string representing the PlainMonthDay
in ISO/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 PlainMonthDay.
Syntax
plainmonthday.toJSON()
Parameters
| NONE |
Return Value
| Type | Description |
| String | The PlainMonthDay in ISO/RFC 9557 format. |
Browser Support
Temporal is a major update to the JavaScript standard (TC39).
It is currently supported in Chrome, Edge, Firefox, and Opera and is expected to reach full availability across browsers before the summer of 2026.
| Chrome 144 |
Edge 144 |
Firefox 139 |
Safari |
Opera 128 |
| Jan 2026 | Jan 2026 | May 2025 | 🚫 | Feb 2026 |
The Safari implementation can be tested in Safari Technology Preview by enabling the --use-temporal runtime flag.
Polyfill
Until Safari support Temporal natively, you can use the official polyfill:
<script
src="https://cdn.jsdelivr.net/npm/@js-temporal/polyfill/dist/index.umd.js">
</script>
