Javascript 在登录中显示自定义错误消息

我想用PHP实现一个简单的登录。但是，我还想自定义登录不正确时的错误消息，例如以红色显示错误消息

Login.php

<?php
    include("connection.php");
    conectar_bd();

    $usr = $_POST['usuario'];
    $pw = md5($_POST['password']);
    $sql = "SELECT usr FROM Client WHERE usr = '$usr'AND password ='$pw'";
    $result = mysql_query($sql, $con);

    if ($fila = mysql_fetch_array($result)) {
        header('Location: menuclient.php');
    } else {
        /* How customize my message error */
    }
?>

validarusario.php

<?php
    include("connection.php");
    conectar_bd();

    $usr = $_POST['usuario'];
    $pw = md5($_POST['password']);
    $sql = "SELECT usr FROM Client WHERE usr = '$usr'AND password ='$pw'";
    $result = mysql_query($sql, $con);

    if ($fila = mysql_fetch_array($result)) {
        header('Location: menuclient.php');
    } else {
        /* How customize my message error */
    }
?>

---

您可以使用
会话
。试试下面的方法

Login.php

  <?php
    session_start();
    if($_SESSON['error']): ?>
    <span>Error : <?php echo $_SESSION['errorMsg']; ?></span>
  <?php endif; ?>
  <form id="frmlogin" name="frmlogin"  method="POST" action="validarUsuario.php">
            <p><input type="text" name="usuario" id="usuario" class="required" maxlength="50" placeholder="Nombre Usuario"></p>
            <p><input type="password" name="password" id="password" class="required"  maxlength="50" placeholder="Password"></p>
             <p id=error> </p>
            <p class="submit"><input type="submit" name="commit" value="Login"></p>
        </form>


错误：





validarusario.php

<?php
session_start();

include("connection.php");
conectar_bd();

$usr = $_POST['usuario'];
$pw = md5($_POST['password']);
$sql = "SELECT usr FROM Client WHERE usr = '$usr'AND password ='$pw'";
$result=mysql_query($sql,$con);

if( $fila=mysql_fetch_array($result) )
{
  header('Location: menuclient.php');
}
else {

  $_SESSION['errorMsg'] = "Wrong username or Password";
  $_SESSION['error'] = true;
  header('Location: Login.php');

}
?>

Sidenote:在散列密码时应该使用salt（）哦，谢谢！我会加盐来保证安全谢谢！我测试了你的代码，但是当我引入一个不正确的登录名时，我被重定向到login.php，错误不会显示。这是你可以将消息发送到另一个页面的唯一方法。请检查会话已正确设置的位置非常感谢！我发现了我的小错误。你的答案很有用。