提交前验证

<form action="MemberServlet" method="post" onsubmit="return validate(this);">

 

function validate(form){
 
 if(form.name.value.trim() == ""){
  alert("您必须输入姓名");
  return false;
 }
 if(form.nickname.value.trim() == ""){
  alert("您必须输入昵称");
  return false;
 }
 if(form.password.value.trim() == ""){
  alert("您必须输入密码");
  return false;
 }
 return true;
}