javascirpt的全选，修改删除判断小例子

javascirpt的全选，修改删除判断小例子

< html >
< head >
     < script  type ="text/javascript" >     
    
        function modifyUser() {
        var count = 0;
        var j = 0
        for(var i=0; i<document.getElementsByName("selectFlag").length; i++) {
            if(document.getElementsByName("selectFlag")[i].checked) {
                j = i;
                count++;
            }
        }
        if(count==0) {
            alert("请选择需要修改的用户");
            return;
        }
        if(count > 1) {
            alert("一次只能修改一个用户");
            return;
        }
        
        //window.self.location = "user_modify.jsp?userId=" + document.getElementsByName("selectFlag")[j].value ;
    }
    
    function deleteUser() {
        var flag = false;
        for(var i=0; i<document.getElementsByName("selectFlag").length; i++) {
            if(document.getElementsByName("selectFlag")[i].checked) {
                flag = true;
                break;
            }
        }
        if(!flag) {
            alert("请选择需要删除的用户");
            return;
        }
        if(window.confirm("确认删除吗？")) {
            alert("删除");
            //with(document.getElementById("userform")) {
                //method = "post";
                //action = "user_maint.jsp?command=delete";
                //submit();
            //}
        }
    }
        
    function checkAll() {
        for(var i=0; i<document.getElementsByName("selectFlag").length; i++) {
            document.getElementsByName("selectFlag")[i].checked = document.getElementById("ifAll").checked
        }
    }
     </ script >
</ head >
< body >
    
     < table  width ="95%"  border ="1"  cellspacing ="0"  cellpadding ="0"     align ="center" >
                 < tr >
                     < td  width ="55" >
                         < input  type ="checkbox"  name ="ifAll"  id ="ifAll"  onClick ="javascript:checkAll()" >
                     </ td >
                     < td >
                        用户代码
                     </ td >

                 </ tr >

                 < tr >
                     < td >
                         < input  type ="checkbox"  name ="selectFlag"  value ="1" >
                     </ td >
                     < td >
                        1
                     </ td >
                 </ tr >
                
                
                 < tr >
                     < td >
                         < input  type ="checkbox"  name ="selectFlag"  value ="2" >
                     </ td >
                     < td >
                        2
                     </ td >
                 </ tr >
             </ table >
         < hr  color ="green" >
             < table  width ="95%"  height ="30"  border ="0"  align ="center"  cellpadding ="0"  cellspacing ="0" >
                 < tr >
                         < td  nowrap >
                         < div  align ="right" >
                             < input  name ="btnAdd"  type ="button"  id ="btnAdd"  value ="添加"  onClick ="addUser()" >
                             < input  name ="btnDelete"  type ="button"     id ="btnDelete"  value ="删除"  onClick ="deleteUser()" >
                             < input  name ="btnModify"  type ="button"     id ="btnModify"  value ="修改"  onClick ="modifyUser()" >
                         </ div >
                     </ td >
                 </ tr >
             </ table >
</ body >
</ html >

全选，删除，修改的判断