title: Regex - Empty field in form validation
body: <p>I have an existing regex:</p>
  
  <pre><code>/^(\d*)(\.(\d*))?$|^$/
  </code></pre>
  
  <p>How do i add/modify a check for empty field - (\s*) to this? - trying to learn regex, did a search but did not find apt resources.</p>