According to
https://tc39.es/proposal-temporal/docs/now.html#instant,

The Temporal.Now.instant() are improved the  accuracy over Date.now from
millisecond to nanosecond, that's need tthe `jerryscript`'s port API to support nanosecond precision
temporal.now require ` nanosecond accuracy`
This is a GitHub Issue
repo:jerryscript
owner:jerryscript-project
Title : temporal.now require ` nanosecond accuracy`
Issue date:

--- start body ---
According to
https://tc39.es/proposal-temporal/docs/now.html#instant,

The Temporal.Now.instant() are improved the  accuracy over Date.now from
millisecond to nanosecond, that's need tthe `jerryscript`'s port API to support nanosecond precision
--- end body ---

None