// assumes jquery is used with $(...)
sbool jqueryUsed(S html) {
  if (!regexpFind("\\$\\s*\\(", html)) false;
  for (S script : allJavascriptFromHTML(html))
    if (jcontains(jsTok(script), "$(")) true;
  for (S tag : codeTokens(htmlTok(html)))
    for (S key, S value : tagParams(tag))
      if (swic(key, "on") && contains(jsTok(value), "$(")) true;
  false;
}