title: Ruby on Rails: putting class with submit_tag
body: <p>I was wondering why we have to add a <code>nil</code> when putting <code>:class =&gt; "class_name"</code></p>
  
  <pre><code>&lt;%= submit_tag nil, :class =&gt; "class_name" %&gt;
  </code></pre>
  
  <p>but for this:</p>
  
  <pre><code>&lt;%= f.submit class: "class-Name" %&gt;
  </code></pre>
  
  <p>I don't need to add the <code>nil</code></p>
  
  <p>Thanks</p>