requireValidDomain

function requireValidDomain(
  domain: unknown,
  message: string = "Expected a valid domain name."
): string;

Labels separated by single dots, with no leading or trailing dot or hyphen and no empty label. It is a syntax check: whether the domain resolves is another question.

isX and nonX answer a question and never interrupt control flow; requireX and requireNonX hand the value back or throw. The scheme is explained in Validation conventions.

Parameters

Parameter	Type	Description
`domain`	`unknown`	The value to validate as a domain name.
`message` (optional) `= "Expected a valid domain name."`	`string`	The message of the exception. A default is used when omitted.

Returns

string — the same value, typed as a domain name.

Throws

Exception	Condition
`IllegalArgumentException`	the value is not a domain name.

Examples

What passes and what does not

requireValidDomain("example.com"); // => "example.com"
requireValidDomain("sub.example.co.uk"); // => "sub.example.co.uk"
requireValidDomain("-example.com"); // throws IllegalArgumentException
requireValidDomain("example..com"); // throws IllegalArgumentException

Source

src/net/path/requireValidDomain.ts

23 September 2026

This documentation was generated with AI (Claude) from the library's source code.

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