select的选中事件 ：
$(document).on("change","#select",function () {
console.log($('#select option:selected').val())
})
&l���,��Աt;div class="out-box"><select id="select"><option>二级请选</option><option value="2.1">2.1</option><option>2.2</option><option>2.3</option><option>2.4</option></select></div><script type="text/javascript"> $(document).on("change",".out-box #select",function () { console.log($('option:selected').val()) })</script>
补充：
常见的js 操作 代码：
http://caibaojian.com/288.html