js 实现checkbox复选框只能单选

// 复选框只能选一个
  function singCheckBox(obj){
        var boxArray = document.getElementsByName('chkAdd');    
        for(var i=0;i<=boxArray.length-1;i++){    
            if(boxArray[i]==obj && obj.checked){    
                boxArray[i].checked = true;    
            }else{    
                boxArray[i].checked = false;    
             }    
         }     
  }