@Nonnull
    static String extractJavaScriptUrlWithIframeResource() throws ParsingException {
        final String iframeUrl;
        final String iframeContent;
        try {
            iframeUrl = "https://www.youtube.com/iframe_api";
            iframeContent = NewPipe.getDownloader()
                    .get(iframeUrl, Localization.DEFAULT)
                    .responseBody();
        } catch (final Exception e) {
            throw new ParsingException("Could not fetch IFrame resource", e);
        }

        try {
            final String hash = Parser.matchGroup1(
                    IFRAME_RES_JS_BASE_PLAYER_HASH_PATTERN, iframeContent);
            return String.format(BASE_JS_PLAYER_URL_FORMAT, hash);
        } catch (final Parser.RegexException e) {
            throw new ParsingException(
                    "IFrame resource didn't provide JavaScript base player's hash", e);
        }
    }
@Test
    public void testExtractJavaScriptUrlIframe() throws ParsingException {
        assertTrue(YoutubeJavaScriptExtractor.extractJavaScriptUrlWithIframeResource()
                .endsWith("base.js"));
    }