jquery取消选择select下拉框示例代码

有三个select下拉框
一个大类,两个小类隐藏,需要在选择大类的时候,小类显示同时清除另外的小类选择的项
这需求有点儿..........

下面是三个select:

<select name="pWaqqqy" id="sel_type" onchange="selectFunction()">
        <option value="">全部</option>
        <option value="7">aa</option>
        <option value="8">bb</option>
    </select>
    <select name="pWay" id="sel_children0" style="display:none;">
        <option value="">全部</option>
        <option value="5">a</option>
        <option value="3">a</option>
        <option value="1">a</option>
        <option value="2">a</option>
        <option value="6">a</option>
    </select>
    <select name="pWay" id="sel_children1" style="display:none;">
        <option value="">全部</option>
        <option value="4">b</option>
    </select>

jquery扩展,调用时,使用$("select").removeSelected();

jQuery.fn.removeSelected = function() {
    this.val("");
};

大类选择框选中时,调用selectFunction()方法:

function selectFunction(){
            if($("#sel_type").val()=="7"){
                 $("#sel_children0").show();
                 $("#sel_children1").hide();
                 $("#sel_children1").removeSelected();
             }else if($("#sel_type").val()=="8"){
                 $("#sel_children1").show();
                 $("#sel_children0").hide();
                 $("#sel_children0").removeSelected();
             }else{
                 $("#sel_children0").hide().removeSelected();
                 $("#sel_children1").hide().removeSelected();
             }
        }

前提是先引入jquery.js文件