Get nid inside preprocess function

Question

My goal is to have an additional region class, when region is rendered on my page--node--9 I am using this template_preprocess_region() function to do this.

But how i can get inside my function ID of page, region is rendered on?

Answer 1

From another implementation of the same hook I found out that the node is actually available through the following. Try it out.

  $node = $variables['node'];

From there you can get node id.