title: pass selected option value from select to php
body: <pre><code>    &lt;style type="text/css"&gt;
      form select {
          display:none;
      }
      form select.active {
          display:block;
      }
      &lt;/style&gt;
      &lt;script type="text/javascript"&gt;
      window.onload = function () {
          var allElem = document.getElementsByName("sl");
          for (i = 0; i &lt; allElem.length; i++) {
              allElem[i].addEventListener('change', toggleDisplay);
          }
     }
      function toggleDisplay(e) {
         var id = 's' + this.value;
          var currentSelect = document.getElementsByClassName("active")[0];
          if (currentSelect) {
              currentSelect.className = "";
          }
          document.getElementById(id).className = "active";
      }    
      &lt;/script&gt;
      &lt;/head&gt;&lt;body&gt;
      &lt;form action="check_a.php"&gt;
      &lt;h2&gt;&lt;b&gt;Source: &lt;/b&gt;&lt;/h2&gt;
      &lt;input type="radio" name="sl"  value="c"&gt;Central&lt;/input&gt;
      &lt;input type="radio" name="sl"  value="h"&gt;Eastern&lt;/input&gt;
      &lt;input type="radio" name="sl" value="w"&gt;Western&lt;/input&gt;
  
      &lt;select id="sc" name="sc"&gt;
      &lt;option value="1"&gt;1&lt;/option&gt;
      &lt;option value="2"&gt;2&lt;/option&gt;
      &lt;/select&gt;
  
      &lt;select id="sh"&gt;
      &lt;option value="3"&gt;3&lt;/option&gt;
      &lt;option value="4"&gt;4&lt;/option&gt;
      &lt;/select&gt;
  
      &lt;select id="sw"&gt;
      &lt;option value="5"&gt;5&lt;/option&gt;
      &lt;option value="6"&gt;6&lt;/option&gt;
      &lt;/select&gt;
      &lt;input type="submit" name="submit" value="submit"/&gt;
  
      &lt;/form&gt;&lt;/body&gt;&lt;/html&gt;
  </code></pre>
  
  <p>there is one radio button whose value displays the specific select box, which is done using javascript.
  the value of  tag needs to be passed to php code. 
  How can i pass the selected option value to php?</p>