title: Pass additional data with submit button
body: <p>I have form, with two buttons:</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true">
  <div class="snippet-code">
  <pre class="snippet-code-html lang-html prettyprint-override"><code> &lt;form action="/Book/Crud" method="post"&gt;
          &lt;input type="text" name="bookInput" /&gt;  
          &lt;button type="submit"&gt;Save&lt;/button&gt;
          &lt;button type="submit"&gt;Save and exit&lt;/button&gt;
      &lt;/form&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p>How can I pass to my controller, or, whatever, additional value, which depends on button?<br>
  <code>&lt;button type="submit" ?????? &gt;Save&lt;/button&gt;</code> What should be here?</p>
  
  <p>I am using Asp.Net Core, with this controller:</p>
  
  <pre><code>public IActionResult Crud(string bookInput)
  {
      //removed code for brevity
  }
  </code></pre>