This particular case doesn't use JavaScript at all. It is just CSS cropping the full URL in a way that when you select and copy it, copies text that it is hidde

This particular case doesn't use JavaScript at all. It is just CSS cropping the full URL in a way that when you select and copy it, copies text that it is hidden. edit to add an example: data:text/html,<div>123<b style="font-size:0">456</b>789</div>