jquery实现全选反选功能

<div id="checkAndInverCheck"> 
<p style="text-align:center; padding-top:15px"> 选择喜欢的兰花品种：</br> 
<input type="checkbox" value="蕙兰">蕙兰   
<input type="checkbox" value="建兰">建兰</br> 
<input type="checkbox" value="寒兰">寒兰   
<input type="checkbox" value="墨兰">墨兰</br>
<input type="checkbox" value="春兰">春兰
<input type="checkbox" value="莲瓣兰">莲瓣兰
 
</div> 
<p style="text-align:center; padding-top:15px"> 
<input type="button" value="全选" name="ay_check" id="ay_check_all"/> 
<input type="button" value="反选" name="ay_check" id="ay_check_invert"/>
</p> 


<script type="text/javascript"> 
//全选 
$("input[name='ay_check']").bind("click",function(){ 
    var btn_id = $(this).attr("id");
    if(btn_id){
        //点击全选按钮
        if(btn_id == "ay_check_all"){
            var inputs = $("#checkAndInverCheck input"); 
            if(inputs.length == 0){ 
                alert("div下没<input>元素，你想全选啥？"); 
            }else{ 
                for(var i in inputs){ 
                    inputs[i].checked=(inputs[i].checked)?"checked":"checked"; 
                } 
            }
        //点击反选按钮
        }else if(btn_id == "ay_check_invert"){
            var inputs = $("#checkAndInverCheck input"); 
            if(inputs.length == 0){ 
                alert("div下没<input>元素，你想反选啥？"); 
            }else{ 
                for(var i in inputs){ 
                    inputs[i].checked=(inputs[i].checked)?"":"checked"; 
                } 
            }　
        }else{
            alert("wrong！！！");
        }
    }
    
}); 
//全选
function checkAll(){ 
    var inputs = $("#checkAndInverCheck input"); 
    if(inputs.length == 0){ 
        alert("div下没<input>元素，你想全选啥？"); 
　　}else{ 
        for(var i in inputs){ 
            inputs[i].checked=(inputs[i].checked)?"checked":"checked"; 
        } 
    } 
} 

//反选 
function invertCheck(){ 
    var inputs = $("#checkAndInverCheck input"); 
    if(inputs.length == 0){ 
        alert("div下没<input>元素，你想反选啥？"); 
    }else{ 
        for(var i in inputs){ 
            inputs[i].checked=(inputs[i].checked)?"":"checked"; 
        } 
    }　 
}