 <p>Maybe you are writing something wrong here:</p> <pre><code>$get(_dropdownID).addClass('dropdownTextDisabled'); </code></pre> <p>shuold be </p> <pre><code>$('#_dropdownID').addClass('dropdownTextDisabled'); </code></pre> <p>does it work in other browsers? What is the variable <code>$get</code> you are calling the method addClass() on?</p>