requireValidSlug

function requireValidSlug(
  value: string | null | undefined,
  message: string = "Expected a valid slug."
): string;

Starts with a letter, then letters, digits, hyphens and underscores — the shape a URL segment or a key can take. Spaces, leading digits and an empty string are rejected.

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
`value`	`string \\| null \\| undefined`	The value to validate.
`message` (optional) `= "Expected a valid slug."`	`string`	The message of the exception. A default is used when omitted.

Returns

string — the same value, typed as a slug.

Throws

Exception	Condition
`IllegalArgumentException`	the value is not a slug.

Examples

What passes and what does not

requireValidSlug("my-page"); // => "my-page"
requireValidSlug("a_1"); // => "a_1"
requireValidSlug("1-page"); // throws IllegalArgumentException
requireValidSlug("my page"); // throws IllegalArgumentException

Source

src/lang/string/requireValidSlug.ts

23 September 2026

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

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