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