简单案例
<body>
<script type="text/javascript">
window.onload = function(){
document.getElementById("pcode").onchange = function(){
alert(this.value);
}
}
</script>
<select id="pcode">
<option value="">>--请选择省份<--</option>
<option value="001">河北省</option>
<option value="002">河南省</option>
<option value="003">湖南省</option>
<option value="004">湖北省</option>
</select>
</body>