//获取选定
function get_selected(cmf){
    var num=0;
    if (cmf.elements["books:list"].length){
      for( var i=0; i<cmf.elements["books:list"].length; i++){
         if (cmf.elements["books:list"][i].checked){
             num++;
         }
      }
    }else{
        if (cmf.elements["books:list"].checked)
            num=1;
    }
    return num;

}
//选择全部
function sla_f(bt){
   cmf=bt.form;
      for( var i=0; i<cmf.elements["books:list"].length; i++){
         cmf.elements["books:list"][i].checked=true;
      
      }
}
//取消选择
function dsla_f(bt){
   cmf=bt.form;
      for( var i=0; i<cmf.elements["books:list"].length; i++){
         cmf.elements["books:list"][i].checked=false;
      
      }
}
//反向选择
function asl_f(bt){
   cmf=bt.form;
      for( var i=0; i<cmf.elements["books:list"].length; i++){
         cmf.elements["books:list"][i].checked=!cmf.elements["books:list"][i].checked;
      
      }
}
//删除图书
function deletebook(cmf){
}

function modifybook(cmf){
   if (get_selected(cmf)==0){
       alert("您没有要提交修改的图书，请先修改吧！")
       return false;
   }
   cmf.method="post"
   cmf.action="./modify_books";
   cmf.submit();
}

function borrow(cmf){
   num = get_selected(cmf)
   if (num==0){
       alert("您还没说借什么书呢？")
       return false;
   }
   
   if (confirm("您要借"+num+"本书吗？")){
       cmf.method="post"
       cmf.action="./b_book_py";
       cmf.submit();       
   }else{
       return false;
   }
}
function RBook_f(cmf){
   num = get_selected(cmf)
   if (num==0){
       alert("您还没选择要还的书呢？")
       return false;
   }
   
   if (confirm("您要还"+num+"本书吗？")){
       cmf.method="post"
       cmf.action="./RBookPy";
       cmf.submit();       
   }else{
       return false;
   }
}