code: @Override
    public String evaluate(String url, String host)
        throws ProxyEvaluationException {
      try {
        StringBuilder script = new StringBuilder(this.source.getScriptContent());
        String evalMethod = " ;FindProxyForURL (\"" + url + "\",\"" + host
            + "\")";
        script.append(evalMethod);
        Object result = this.engine.eval(script.toString());
        return (String) result;
      } catch (Exception e) {
        log.log(Level.INFO, "JS evaluation error.", e);
        throw new ProxyEvaluationException("Error while executing PAC script: "
            + e.getMessage(), e);
      }
  
    }
docs: ***********************************************************************
  Evaluates the given URL and host against the PAC script.
  
  @param url
  the URL to evaluate.
  @param host
  the host name part of the URL.
  @return the script result.
  @throws ProxyEvaluationException
  on execution error.
  **********************************************************************