Remove Javascript comments from the script tag of an HTML, ignoring content from other tags (e.g., base 64 images)

Question

I need to ignore the tags img because some images come in Base64 and contain // which are recognized as comments and are removed, breaking all HTML code.

function limpa_html($html){
    $pattern = '/(?:(?:\/\*(?:[^*]|(?:\*+[^*\/]))*\*+\/)|(?:(?<!\:|\\\|\'|\")\/\/.*))/';
    $html = preg_replace($pattern, '', $html); //apaga comentarios em js
    return $html;
}

This is the function suits me super well, but images like <img src="data:image/jpeg;base64,/9j/4AAQSkZJRgAAQABAAD/2wBDAAQgHBwcJCQg// break HTML. The idea would be to ignore tags img or limit code only to tags script, but I do not understand from regex to that point.

Here a simulation of what happens:

<script>

// This is a comment
/* This is another comment */

// The following is not a comment
var src="//google.com"; 

</script>
<img src="data:image/jpeg;base64,/9j/4AAQSkZJRgABAQAAAQABAAD/2wBDAAgGBgcGBQgHBwcJCQg//ejhdbjkebdklebdklenbdknedklnekdlelde>

In the example above, the final tag snippet img (//ejhdbjkebdklebdklenbdknedklnekdlelde) is also removed.

Answer 1

Instead of using regex across HTML, you can use DOMDocument to get only the tags script, and apply the regex only to them.

This way you guarantee that you will replace only the Javascript code, without having to worry about the other tags. Example:

$text = <<<TEXTO
<script>

// This is a comment
/* This is another comment */

// The following is not a comment
var src="//google.com"; 

</script>
<img src="data:image/jpeg;base64,/9j/4AAQSkZJRgABAQAAAQABAAD/2wBDAAgGBgcGBQgHBwcJCQg//ejhdbjkebdklebdklenbdknedklnekdlelde>
TEXTO;

// mudar o nome da função e do parâmetro para deixar bem claro o que ela faz
function limpa_comentarios($jsCode) {
    $pattern = '/(?:(?:\/\*(?:[^*]|(?:\*+[^*\/]))*\*+\/)|(?:(?<!\:|\\\|\'|\")\/\/.*))/';
    return preg_replace($pattern, '', $jsCode); // apaga comentários em js
}

// carrega o HTML
$dom = new DOMDocument;
$dom->loadHtml($text); // $text é uma string contendo o HTML
$xpath = new DOMXPath($dom);
// procura as tags script e aplica a regex somente nelas
foreach ($xpath->query("//script") as $script) {
    $newContent = limpa_comentarios($script->nodeValue);
    // substitui o conteúdo do script
    $script->nodeValue = '';
    $script->appendChild($dom->createTextNode($newContent));
}
echo $dom->saveHTML();

But if the idea is minify HTML/JS, you might want to search for dedicated libs, instead of trying to do everything manually.