<script>
function deleteRow(link){
 var b =  confirm("确定删除？")
 if(!b)
   return;
 
var table = document.getElementById("heroTable");
var td = link.parentNode;
var tr = td.parentNode;
var index=tr.rowIndex;
table.deleteRow(index);
 
}
</script>
<table width="100%" border = "1" cellspacing="0" id="heroTable">
 
<tr >
   <td width="50%">英雄名称</td>
   <td>
       操作
   </td>
</tr>
 
<tr >
   <td>盖伦</td>
   <td>
      <a href="#" onclick="deleteRow(this)">删除</a>    
    </td>
</tr>
 
<tr >
   <td>提莫</td>
   <td>
      <a href="#" onclick="deleteRow(this)">删除</a>    
    </td>
</tr>
 
<tr >
   <td>祈求者</td>
   <td>
      <a href="#" onclick="deleteRow(this)">删除</a>    
    </td>
</tr>
 
</table>

<form method="post" action="/study/login.jsp" onsubmit="return login()">
账号：<input id="name" type="text" name="name"> <br/>
密码：<input id="password" type="password" name="password" > <br/>
<input type="submit" value="登陆">
</form>
   
<script>
  function login(){
   var name = document.getElementById("name");
   if(name.value.length==0){
     alert("用户名不能为空");
     return false;
   }
 
   var password = document.getElementById("password");
   if(password.value.length==0){
     alert("密码不能为空");
     return false;
   }
 
   return true;
 
  }
</script>

<form method="post" action="/study/register.jsp" onsubmit="return register()">
账号：<input id="name" type="text" name="name">
<br><br>
<input type="submit" value="注册">
<br>
</form>
    
<script>
  function register(){
   var name = document.getElementById("name");
   if(name.value.length<3){
     alert("用户名至少需要3位长度");
     return false;
   }
  
   return true;
  
  }
</script>

<form method="post" action="/study/register.jsp" onsubmit="return register()">
账号：<input id="name" type="text" name="name">
<br><br>
 
年龄：<input id="age" type="text" name="age">
<br><br>
<input type="submit" value="注册">
<br>
</form>
     
<script>
  function register(){
   var name = document.getElementById("name");
   if(name.value.length<3){
     alert("用户名至少需要3位长度");
     return false;
   }
 
   var age = document.getElementById("age");
   if(age.value.length==0){
     alert("年龄不能为空");
     return false;
   }
   if(isNaN(age.value)){
     alert("年龄必须是数字");
     return false;
   }
   
   return true;
   
  }
</script>