CheckBox 选中判断及实现单选功能

            ///功能：判断是否有选中项；
            ///参数：frm - 当前表单Form；idVal - 要查找的CheckBox的id；
            ///返回：True/False；
            ///调用：<INPUT type="submit" value="提交" id="btnS" runat="server" 
                                    onclick="JavaScript:return confirmSel(this.form, 'chkSel');">
            ///说明：'chkSel' - 将判断所有id包含'chkSel'的控件；
            function confirmSel(frm, idVal) 
            {        
                // loop through all elements
                var IsChecked;
                IsChecked=false;
                for (i=0; i<frm.length; i++) 
                {
                    // Look for our checkboxes only
                    if (frm.elements[i].id.indexOf (idVal) !=-1) 
                    {                
                        // If any are checked then confirm alert, otherwise nothing happens
                        if(frm.elements[i].checked) 
                        {
                            IsChecked=true;
                            return true;
                            //return confirm ('确定要提交所选择的记录吗？')
                        }                    
                    }
                }            
                if(IsChecked==false)
                {
                    alert('请选择要进行操作的行!!!');
                    return false;                    
                }
            }
            
            ///功能：对CheckBox实现单选功能；
            ///参数：frm - 当前表单Form；chkVal - 当前CheckBox状态:选中True,不选中False；idVal - 当前CheckBox的id；
            ///返回：True/False；
            ///调用：<input type="checkbox" id='chkSel' onpropertychange='JavaScript:selChk(this.form,this.checked,this.id);' title="" runat="Server">            
            ///说明：hdnChkID - Hidden隐藏框，用于存放上次选中项CheckBox的id；
            function selChk(frm,chkVal,idVal)
            {                        
                if(chkVal == true)  //如果当前CheckBox被选中
                {         
                     //将上次选中的CheckBox的id赋给变量lstChkID                       
                    var lstChkID = document.getElementById("hdnChkID").value;
                     //记录当前CheckBox的id
                    document.getElementById("hdnChkID").value = idVal;
                    if(lstChkID!='')
                    {
                        document.getElementById(lstChkID).checked = false;
                    }
                }                    
            }