alert不在JS中显示

alert not displaying in JS

本文关键字：显示 JS 不在 alert 更新时间：2023-09-26

警报未按预期工作!我不知道为什么……我正试图评估客户端的形式。我试过getElementsById, getElementsByName。我哪里做错了?我确信控制流经过validate()在validate方法中显示了一条警告语句!

下面是我的代码:

     <%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1" errorPage="Error.jsp"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<script type="text/javascript">
function validate() {
    var uname = document.getElementById("uname").value;
    var email = document.getElementById("email").value.indexof('@');
    var pass = document.getElementById("pass").value;
    var rpass = document.getElementById("rpass").value;
    submitOK = true;
    if (uname.length == 0) {
      alert("Username cannot be empty")
      submitOK = false;
    }
    if (email == -1) {
      alert("Not a valid email");
      submitOK = false;
    }
    if (pass.length === 0) {
      alert("Password cannot be empty");
      submitOK = false;
    }
    if (pass != rpass) {
      alert("passwords don't match");
      submitOK = false;
    }
    return submitOK;
  }
</script>
<title>Register</title>
</head>
<body>
<h1>Register</h1>
<br />
<form action="RegInt.jsp" method="post" onsubmit="return validate()">
Enter UserName : <input type="text" name="uname" id="uname" value='${ param.uname}'placeholder="Enter Name" ><br/><br/>
Enter Email:     <input type="email" name="email" id = "email" value='${param.email}'placeholder="Enter Email"><br/><br/>
Enter Password:  <input type="password" name="pass" id = "pass" value='${param.pass}'placeholder="Enter password"><br/><br/>
Repeat Password: <input type="password" name="rpass" id = "rpass" value='${param.rpass}'placeholder="Repeat Password"/><br/>
    <br/><br/>
<input type="submit"/>
</form>
<h4>${errorMsg}</h4>
</body>
</html>

alret和indexOf的拼写
getElementById是单数
submitOK="false"设置submitOK为真，因为非空字符串为真。使用submitOK=false
你问问题时没有返回submitOK

    function validate() {
      var uname = document.getElementById("uname").value;
      var email = document.getElementById("email").value.indexOf('@');
      var pass = document.getElementById("pass").value;
      var rpass = document.getElementById("rpass").value;
      submitOK = true;
      if (uname.length == 0) {
        alert("Username cannot be empty")
        submitOK = false;
      }
      if (email == -1) {
        alert("Not a valid email");
        submitOK = false;
      }
      if (pass.length === 0) {
        alert("Password cannot be empty");
        submitOK = false;
      }
      if (pass != rpass) {
        alert("passwords don't match");
        submitOK = false;
      }
      return submitOK;
    }

<h1>Register</h1>
<br />
<form action="RegInt.jsp" method="post" onsubmit="return validate()">
  Enter UserName :
  <input type="text" name="uname" id="uname" value='${ param.uname}' placeholder="Enter Name">
  <br/>
  <br/>Enter Email:
  <input type="email" name="email" id="email" value='${param.email}' placeholder="Enter Email">
  <br/>
  <br/>Enter Password:
  <input type="password" name="pass" id="pass" value='${param.pass}' placeholder="Enter password">
  <br/>
  <br/>Repeat Password:
  <input type="password" name="rpass" id="rpass" value='${param.rpass}' placeholder="Repeat Password" />
  <br/>
  <br/>
  <br/>
  <input type="submit" />
</form>

首先检查拼写并改正。然后对所有字段进行注释，并开始逐行进行故障排除。你会赢的。问候!