title: How can I match any number OR string combined in regex?
body: <p>I'm trying to create a filter pattern that would match:</p>
  
  <pre><code>site39.social-buttons.com
  site.social-buttons.com
  123.social-buttons.com
  </code></pre>
  
  <p>However I cannot find anywhere how to use <code>any number or letter</code> in regex. I have found for <code>letters</code> only e.g <code>[a-g]</code></p>
  
  <pre><code>(\.social\-buttons).com
  </code></pre>
  
  <p>What goes before the <code>\.</code> to match the above URLs?</p>