formatHttp

Signature

formatHttp(value: string): string

import { formatHttp } from "@northguild/gmt/utc/format";

Format a UTC ISO 8601 datetime string as an RFC 7231 IMF-fixdate — the

• fixed grammar HTTP headers like Last-Modified/Date/Expires require.
• Fixed grammar, not a display format. RFC 7231 mandates English weekday/month abbreviations and a literal GMT suffix regardless of caller locale — there is no locale-appropriate alternative ordering to lose (see roadmap issues/J.md Decision 1 / J13).
• Always GMT; HTTP-date carries no offset variation to preserve.
• Fractional seconds in value are truncated — IMF-fixdate has no sub-second field.
• Day, hour, minute, and second are always zero-padded to 2 digits; year is zero-padded to 4 digits.

Parameters

Parameter	Type	Description
value	string	UTC ISO 8601 datetime string (e.g. “2024-03-15T14:30:00Z”)

Returns

RFC 7231 IMF-fixdate string, or “” on invalid input

Examples

formatHttp("2024-03-15T14:30:00Z") // "Fri, 15 Mar 2024 14:30:00 GMT"
formatHttp("2024-03-15T14:30:00.500Z") // "Fri, 15 Mar 2024 14:30:00 GMT"
formatHttp("invalid") // ""

Source

utc/format/formatHttp.ts