JavaScript Modules are not handled correctly

[bavarianbytes]

EcmaScript modules require a rel=modulepreload instead of rel=preload: https://web.dev/articles/modulepreload

It would be nice if the extension would reflect that. An simple approach would be to check if the file extension is .mjs. Something like this in Classes/Http/ResourcePusher.php:addPreloadHeaderToResponse():

if(str_contains($uri, '.mjs')) {
    return $response->withAddedHeader('Link', '<' . htmlspecialchars(PathUtility::getAbsoluteWebPath($uri)) . '>; rel=modulepreload; as=' . $type);
} else {
    return $response->withAddedHeader('Link', '<' . htmlspecialchars(PathUtility::getAbsoluteWebPath($uri)) . '>; rel=preload; as=' . $type);
}

[bmack]

sounds good, do you want to create a PR for that?

[bavarianbytes]

Done! :-)