formatRfc2822

Signature

formatRfc2822(value: string): string

Format a zoned ISO 8601 datetime string as an RFC 5322 (RFC 2822) date-time — the fixed grammar email Date: headers require.

• Fixed grammar, not a display format. RFC 5322 mandates English weekday/month abbreviations and a numeric +HHMM/-HHMM offset regardless of caller locale — there is no locale-appropriate alternative ordering to lose, so this does not conflict with GMT’s exclusion of a general token formatter.
• Uses the input’s own UTC offset at that instant (DST-aware); never emits an obsolete named zone like “GMT” or “EST” on output, only numeric.
• Day, hour, minute, and second are always zero-padded to 2 digits; year is zero-padded to 4 digits.
• Fractional seconds are truncated: second = 2DIGIT has no fraction.
• Returns "" when the offset is not a whole number of minutes (local mean time, e.g. Africa/Monrovia −00:44:30 before 1972): zone is ("+" / "-") 4DIGIT, meaning ±(hh·60 + mm) minutes.
• Returns "" for a negative year: year = 4*DIGIT has no sign. Years of five or more digits are written in full.
• Compatibility: before 1.16.0 these inputs gave strings outside the grammar ("-0044.5", "00-1"). For the value itself use Temporal.ZonedDateTime#toString().

Parameters

Parameter	Type	Description
value	string	zoned ISO 8601 datetime string (e.g. “2024-03-15T14:30:00-04:00[America/New_York]”)

Returns

RFC 5322 date-time string, or "" on invalid input, a sub-minute offset or a negative year

Examples

import { formatRfc2822 } from "@northguild/gmt/zoned/format";

formatRfc2822("2024-03-15T14:30:00-04:00[America/New_York]") // "Fri, 15 Mar 2024 14:30:00 -0400"

value

output

 

Source

zoned/format/formatRfc2822.ts