content-negotiation

HTTP Accept header negotiation with q-values, specificity ordering, and media-type matching per RFC 9110.

Quick Start

import { parseAccept, negotiate } from "content-negotiation";

const accept = "text/html, application/json;q=0.9";
const available = ["text/html", "application/json", "text/plain"];

const best = negotiate(accept, available); // → "text/html"

API

parseAccept(header: string): MediaType[]

Parse Accept header; returns sorted by specificity then q-value.

Specificity: exact type/subtype > type/* > /

parseAcceptLanguage(header: string): ParsedLanguage[]

Parse Accept-Language header; sorted by q-value.

negotiate(acceptHeader: string, available: string[]): string | null

Find best match from available options, or null if none match.

Limits

• Parameters parsed but not matched during negotiation
• No Accept-Encoding or Accept-Charset (extend with parseAccept)
• Language subtags not matched (exact match only)

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