- var_dump: documentation ( source)
- preg_replace: documentation ( source)
<?php
$cleanHtml = '<div><article>foo</article><foo><foobar></foobar></foo></div>';
var_dump($cleanHtml);
$cleanHtml = preg_replace("/<[a-z]+>/", "$1\n", $cleanHtml);
var_dump($cleanHtml);