title: How can change disabled style for select box with javascript
body: <p>I want to change the second's select box disabled style when the first select box is changed but I can't. Please help me.</p>
  
  <pre><code>&lt;html&gt;
      &lt;body&gt;
          &lt;select onchange="a()" id="1"&gt;
              &lt;option&gt;Choose&lt;/option&gt;
              &lt;option&gt;1&lt;/option&gt;
              &lt;option&gt;2&lt;/option&gt;
          &lt;/select&gt;
          &lt;select id="2" disabled="true"&gt;
              &lt;option&gt;one&lt;/option&gt;
              &lt;option&gt;two&lt;/option&gt;
          &lt;/select&gt;
          &lt;script&gt;
              function a(){
                  if(document.getElementById('1').value!="Choose"){
                      document.getElementById('2').style.background="yellow";
                      document.getElementById('2').style.disabled="false";
                  }
              }
          &lt;/script&gt;
     &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>