URL validation utilities

uri-validator.ts

/**
 * Validate potentially relative URL
 *
 * @param input - URL to validate
 * @returns true if URL is valid and doesn't need additional encoding
 */
const isValidURL = (input: string): boolean => {
  try {
    const { href, pathname, host, origin } = new globalThis.URL(
      input,
      'https://-',
    );
    // If href value changes (absolute) or pathname value changes (relative),
    // then the URL is invalid or requires additional encoding
    return host === '-'
      ? // relative URL
        input === pathname
      : // absolute URL
        input === href || input === origin;
  } catch (ex) {
    return false;
  }
};

url-validator.ts

const removeProtocol = ({
  href,
  protocol,
}: Pick<URL, 'href' | 'protocol'>): string =>
  href.slice(protocol.length).replace(/^\/*/, '');

const matchWithOptionalEndingSlash = (input: string, parsed: string): boolean =>
  input === parsed || (!input.endsWith('/') && parsed === `${input}/`);

/**
 * Check whether a given URL is absolute and valid
 *
 * @param input - URL to check
 * @returns Whether the URL is absolute and valid
 */
const isValidAbsoluteURL = (input: string): boolean => {
  try {
    const url = new URL(input);
    const { href, protocol, origin } = url;
    // origin matches
    if (input.startsWith(origin)) {
      return matchWithOptionalEndingSlash(input, href);
    }
    // origin doesn't match (extra slashes were potentially removed)
    if (input.startsWith(protocol)) {
      return matchWithOptionalEndingSlash(
        removeProtocol({ href: input, protocol }),
        removeProtocol(url),
      );
    }
    return false;
  } catch (ex) {
    return false;
  }
};