TYPO3 Core

What I also want to know is in which browser this happens.

Current 6.2 git master and current Firefox stable (extensions: Firebug and web Developer Toolbar).

I check the configuration... BE|CompressionLevel is zero?!
Are there any other manipulation mechanisms that transofrm the javascript?

Regards,
Tim

We believe you, but can you please find out about your settings.

BE compression level has nothing to do with this. It just controls (if the zlib extension is installed) whether the "compressed" JS file is again compressed with gzip.

// decide whether we should create gzipped versions or not
$compressionLevel = $GLOBALS['TYPO3_CONF_VARS'][TYPO3_MODE]['compressionLevel'];
// we need zlib for gzencode()
if (extension_loaded('zlib') && $compressionLevel) {
    $this->createGzipped = TRUE;

protected function writeFileAndCompressed($filename, $contents) {
    // write uncompressed file
    GeneralUtility::writeFile(PATH_site . $filename, $contents);
    if ($this->createGzipped) {
        // create compressed version
        GeneralUtility::writeFile(PATH_site . $filename . '.gzip', gzencode($contents, $this->gzipCompressionLevel));
    }
}

Sorry... my fault. It was no clean installation... Anybody overwrite the ResourceCompressor->compressJsFile function and add JSMin compression. Bad idea, even if it worked before.

So this is not a core bug and should be closed!
Thanks for the hint!

Regards,
Tim