| import type { Nullable } from '../utils'; | |
| /** | |
| * Transforms a domain name into a canonical domain name. The canonical domain name is a domain name | |
| * that has been trimmed, lowercased, stripped of leading dot, and optionally punycode-encoded | |
| * ({@link https://www.rfc-editor.org/rfc/rfc6265.html#section-5.1.2 | Section 5.1.2 of RFC 6265}). For | |
| * the most part, this function is idempotent (calling the function with the output from a previous call | |
| * returns the same output). | |
| * | |
| * @remarks | |
| * A canonicalized host name is the string generated by the following | |
| * algorithm: | |
| * | |
| * 1. Convert the host name to a sequence of individual domain name | |
| * labels. | |
| * | |
| * 2. Convert each label that is not a Non-Reserved LDH (NR-LDH) label, | |
| * to an A-label (see Section 2.3.2.1 of [RFC5890] for the former | |
| * and latter), or to a "punycode label" (a label resulting from the | |
| * "ToASCII" conversion in Section 4 of [RFC3490]), as appropriate | |
| * (see Section 6.3 of this specification). | |
| * | |
| * 3. Concatenate the resulting labels, separated by a %x2E (".") | |
| * character. | |
| * | |
| * @example | |
| * ``` | |
| * canonicalDomain('.EXAMPLE.com') === 'example.com' | |
| * ``` | |
| * | |
| * @param domainName - the domain name to generate the canonical domain from | |
| * @public | |
| */ | |
| export declare function canonicalDomain(domainName: Nullable<string>): string | undefined; | |