Code Snippet
<select id="Select1">
<option value="0">aaa</option>
<option value="1">bbb</option>
<option value="2">ccc</option>
</select>
<script type="text/jscript">
function test()
{
if (!document.getElementById("Select1").value)
{
alert("Please select a customer.");
return false;
}
else
{
alert("selected");
return true;
}
}
</script>