javascript - set select option value to null
<p>I have to disable all the <code>select</code> menus in a <code>div</code> and also set their value to <code>null</code>.</p>

<p>I am using the following code to disable the select menus:</p>

<pre><code>  var div_contents =document.getElementById("div1");
  var elements = div_contents.getElementsByTagName("select");
  for (i=0; i&lt;elements.length; i++) {
      elements[i].disabled = true;
  }
</code></pre>

<p>However, I am not able to set the value of the select tag to <code>null</code>.</p>

<p>Also I don't have the <code>null</code> option inside the <code>select</code> tag:</p>

<pre><code>&lt;select id="test1" name="test1"&gt;
    &lt;option value="a"&gt;aa&lt;/option&gt;
    &lt;option value="b"&gt;bb&lt;/option&gt;
    &lt;option value="c"&gt;cc&lt;/option&gt;
&lt;/select&gt;
</code></pre>

<p>How can I set the value of a <code>select</code> list to <code>null</code>, given that I don't have the <code>null</code> option?</p>
