javascript实现全选,反选

     <script type="text/javascript" language="javascript">
        function selectBox(selectType){
        var checkboxis = document.getElementsByName("Checkbox");
        if(selectType == "reverse"){
            for (var i=0; i<checkboxis.length; i++){
                //alert(checkboxis[i].checked);               
                checkboxis[i].checked = !checkboxis[i].checked;
            }
        }
        else if(selectType == "all")
        {
            for (var i=0; i<checkboxis.length; i++){
                //alert(checkboxis[i].checked);               
                checkboxis[i].checked = true;
            }
        }
     }
    
     function deleteSelect(){       
        var aryId = [];
        var checkboxis = document.getElementsByName("Checkbox");
        for (var i=0; i<checkboxis.length; i++){
            //alert(checkboxis[i].checked);
            if(checkboxis[i].checked)
                aryId.push(checkboxis[i].value);
        }
        if(aryId.length > 0)
        {
            if(confirm("该操作比较危险请慎重\n\n确实要删除吗"))
            location.href = "Admin_Agent.aspx?action=deleteQuestion&aryId=" + aryId.join("\",\"");
        }else
        {
            alert("请选择要删除的用户!");
        }   
     }
     </script>
<input id="Button3" type="button" value="全选" onclick="selectBox('all')" />
<input id="Button1" type="button" value="反选" onclick="selectBox('reverse')" />
<input id="Button2" type="button" value="删除所选" onclick="deleteSelect()" />