title: Adding new option to select menu
body: <p>This is a very simple select bar. Why is it not working?</p>
  
  <pre><code>&lt;html&gt;
  &lt;form&gt;
      &lt;label&gt;
          &lt;select id="sel1"&gt;
              &lt;option&gt; op1 &lt;/option&gt;
              &lt;option&gt; op2 &lt;/option&gt;
              &lt;option&gt; op3 &lt;/option&gt;
          &lt;/select&gt;
          &lt;input onclick="s()" type="submit" value=" ok! "&gt;
      &lt;/label&gt;
  &lt;/form&gt;
  &lt;script&gt;
      function s(){
          document.getElementById("sel1").innerHTML += "&lt;option&gt; op4 &lt;/option&gt;";
      }
  &lt;/script&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>If I want people to add new option, I need to put some variable on it. How can I add php variable instead of op4, op5, etc?</p>