How do I properly check whether PHP is properly configured to use DOMDocument?

I have a script that uses DOMDocument. In some environments, it fails, presumably due to some module is not loaded. What I’m trying to do is to provide a user of this script instructions to fix this behavior.

Here’s a minimal script to reproduce the problem:

<?php
  echo 'start!';
  try {
    $doc = new DOMDocument();
  } catch (Exception $e) {
    echo 'catched';
  }
  echo 'end';
?>

If I open it in browser (served by my current server, involving Nginx), I see just start! (and the return code is 500; same output if I omit try..catch). So the problem is not only in detecting whether the right module is installed (should I use extension_loaded('dom') to check it?), but also the fact that try..catch doesn’t seem to work (I don’t get catched in the output; I’m using PHP 7.4.3 in the current case).

Any suggestions of how should I process this case correctly?

>Solution :

You can test for the class with class_exists()

Eg

if (!class_exists('DOMDocument')){
   echo "Please install DOMDocument";
   exit;
}