How can I get the node ID from a path alias? I want to be able to get the nid but the only information I have is http://example.com/this-is-the-alias.

Is there a way to get either the internal path of /node/*  for that alias if I am not on the page?  Or is there a way to just get the nid from that alias right away?
I'm not sure if there's a direct function, but one route is to use the path alias manager service to lookup the internal path then regex it for a valid node id to perform an object load on: 

$path = \Drupal::service('path.alias_manager')-&gt;getPathByAlias('/this-is-the-alias');
if(preg_match('/node\/(\d+)/', $path, $matches)) {
  $node = \Drupal\node\Entity\Node::load($matches[1]);
}