/**
 * Converts a string to `kebab-case`.
 *
 * Splits the input into word tokens via {@link stringSplitWords}, lowercases each
 * token, and joins them with a hyphen. Returns an empty string when the input
 * contains no word tokens.
 *
 * @example
 * stringToKebabCase('FooBar')         // 'foo-bar'
 * stringToKebabCase('foo_bar')        // 'foo-bar'
 * stringToKebabCase('XMLHttpRequest') // 'xml-http-request'
 * stringToKebabCase('xhr2 request')   // 'xhr-2-request'
 * stringToKebabCase('---')            // ''
 */
export declare function stringToKebabCase(str: string): string;