custom-mime-router.php

<?php

// php -S localhost:80 -t www www/index.php

$Root = dirname(__FILE__);
$Mime = NULL;
$File = match($_SERVER['REQUEST_URI']) {
	'/'     => "{$Root}/index.html",
	default => "{$Root}{$_SERVER['REQUEST_URI']}"
};
$Info = pathinfo($File);

if(file_exists($File))
if(array_key_exists('extension',$Info)) {
	$Mime = match($Info['extension']) {
		'js'      => 'text/javascript',
		'babylon' => 'application/json',
		'fx'      => 'plain/text',
		default   => mime_content_type($File)
	};

	if($Mime) {
		header(sprintf('Content-Type: %s',$Mime));
		readfile($File);
		return TRUE;
	}
}

return FALSE;