title: Regex allow letters and space only in html input box
body: <p>I want to allow only letters and space in input box like "john deo". but the above doesn't work with below Regex and it is not allowing space.</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;!DOCTYPE html"&gt;
  &lt;html xmlns="http://www.w3.org/1999/xhtml"&gt;
  &lt;head&gt;
  &lt;title&gt;Untitled Document&lt;/title&gt;
  &lt;/head&gt;
  
  &lt;body&gt;
  &lt;label&gt;full name
  &lt;input type="text" name="textfield" onkeydown="return /[a-z]/i.test(event.key)"
      onblur="if (this.value == '') {this.value = '';}"
      onfocus="if (this.value == '') {this.value = '';}"/&gt;
  &lt;/label&gt;
  &lt;/body&gt;
  &lt;/html&gt;</code></pre>
  </div>
  </div>
  </p>