/** Returns the result of replacing HTML reserved characters in `str` with their HTML encoded escape values.
 * @returns an empty string if `str` is `undefined` or `null`.
 * @example
 * ```ts
 * htmlEncode('Text with WAVE breaking <h1>text</h1> in it.')
 * // Returns: 'Text with WAVE breaking &lt;h1&gt;text&lt;/h1&gt; in it.'
 * ``` */
export declare function htmlEncode(str: string | number | Date | boolean | undefined | null): string;
export declare function htmlDecode(str: string): string;