fromFileTime

Signature

fromFileTime(value: bigint): string

Convert a Windows FILETIME back to an ISO 8601 instant string.

• value counts 100-nanosecond intervals since 1601-01-01T00:00:00Z.
• The accepted range is 0n to 2^63 − 1, 1601-01-01 to +030828-09-14T02:48:05.4775807Z. FILETIME is a pair of DWORDs, so a negative value is rejected rather than read as a pre-1601 instant. Values from 2^63 up are rejected too: Microsoft’s FileTimeToSystemTime requires a value “less than 0x8000000000000000”, and SetFileTime uses 0xFFFFFFFFFFFFFFFF (2^64 − 1) as its “do not modify” marker.
• To decode the raw unsigned count anyway, for example to inspect a marker, compute fromNanoseconds((value - 116444736000000000n) * 100n).
• Exact in this direction — 100 ns is coarser than the nanoseconds an ISO string carries, so nothing is rounded. The loss, if any, happened in toFileTime.
• Returns "" on invalid input.

Parameters

Parameter	Type	Description
value	bigint	100-nanosecond intervals since 1601-01-01 (bigint, 0n to 2^63 − 1)

Returns

ISO 8601 instant string (UTC), or "" on invalid input

Examples

import { fromFileTime } from "@northguild/gmt/precision/convert";

fromFileTime(0n) // "1601-01-01T00:00:00Z" — the FILETIME epoch

value

output

 

Source

precision/convert/fromFileTime.ts