3v4l.org

run code in 200+ php & hhvm versions
Bugs & Features
<?php $a = [ '<a href="www.onte.pl">Test</a>', '<a href="http://www.onet.pl">Test</a>', '<a href=" http://wp.pl">T</a>', '<a href="onet.pl" title="qweqweqe">qweqwe</a>', ]; foreach ($a as $k) { echo strip_tags($k, '<a>') , PHP_EOL; }
based on d9acR
Output for 5.6.0 - 5.6.30, hhvm-3.15.4, 7.0.0 - 7.2.6
<a href="www.onte.pl">Test</a> <a href="http://www.onet.pl">Test</a> <a href=" http://wp.pl">T</a> <a href="onet.pl" title="qweqweqe">qweqwe</a>