title: How to disable submit button once it has been clicked?
body: <p>I have a submit button at the end of the form.</p>
  
  <p>I have added the following condition to the submit button:</p>
  
  <pre><code>onClick="this.disabled=true;
  this.value='Sending…';
  this.form.submit();"
  </code></pre>
  
  <p>But when it moves to the next page, the parameters did not pass and null values are passed.</p>