Javascript 为什么我的脚本标签中总是有未定义的变量：errorEmpty和errorEmail？

为什么我的脚本标签中总是有未定义的变量：errorEmpty和errorEmail

我正在尝试使用ajax验证注册表单。但我在以下方面不断得到一个未定义的变量错误：

var errorEmpty = "<?php echo $errorEmpty; ?>";
var errorEmail = "<?php echo $errorEmpty; ?>"; 

var errorEmpty=“”；
var errorEmail=“”；

任何建议都将不胜感激。多谢各位

<?php  
session_start();
include '../dbh.php';


if (isset($_POST['submit'])) {
    {$first = $_POST['first'];
    $last = $_POST['last'];
    $email = $_POST['email'];
    $pwd = $_POST['pwd'];

    $errorEmpty == false;
    $errorEmail == false;


if (empty($first) || empty($last) || empty($email) || empty($pwd)) {
 echo "<span class='form-error'>Please fill out all fields!</span>";
 $errorEmpty == true;
}

elseif (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
 echo "<span class='form-error'>Please enter a valid email address!</span>";
 $errorEmail == true;
} 


else {$sql = "SELECT email FROM user WHERE email='$email'";
$result = mysqli_query($conn, $sql);
$emailcheck = mysqli_num_rows($result);
}

if ($emailcheck > 0) {
 echo "Email address already exists";
 header("Location: ../index.php?error=email");
 exit();
}


else {
 $encryptpwd = password_hash($pwd, PASSWORD_DEFAULT);
 $sql = "INSERT INTO user (first, last, email, pwd)
 VALUES ('$first', '$last', '$email', '$encryptpwd')";
 $result = mysqli_query($conn, $sql);header("Location: ../profile.php");

    }

}

} 


?>


<script> 
$("#signup-first, #signup-last, #signup-email, #signup-pwd").removeClass ("input-error"); 

    var errorEmpty = "<?php echo $errorEmpty; ?>";
    var errorEmail = "<?php echo $errorEmpty; ?>"; 

 if (errorEmpty == true) {
  $("#signup-first, #signup-last, #signup-email, #signup-pwd").addClass("input-error");
 }

 if (errorEmail == true) {
  $("#signup-email").addClass("input-error");
 } 

 if (errorEmpty == false && errorEmail == false) {
  $("#signup-first, #signup-last, #signup-email, #signup-pwd").val("");
}

 </script>

---

在上面的页面顶部定义
$errorEmpty
和
$errorEmail

if (isset($_POST['submit'])) {

}

在此页面上方的顶部定义
$errorEmpty
和
$errorEmail

if (isset($_POST['submit'])) {

}

=
是比较运算符。要给任何变量赋值，只需使用single
=

<?php  
session_start();
include '../dbh.php';


if (isset($_POST['submit'])) {
    {$first = $_POST['first'];
    $last = $_POST['last'];
    $email = $_POST['email'];
    $pwd = $_POST['pwd'];

    $errorEmpty = false;
    $errorEmail = false;


if (empty($first) || empty($last) || empty($email) || empty($pwd)) {
 echo "<span class='form-error'>Please fill out all fields!</span>";
 $errorEmpty = true;
}

elseif (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
 echo "<span class='form-error'>Please enter a valid email address!</span>";
 $errorEmail = true;
} 


else {$sql = "SELECT email FROM user WHERE email='$email'";
$result = mysqli_query($conn, $sql);
$emailcheck = mysqli_num_rows($result);
}

if ($emailcheck > 0) {
 echo "Email address already exists";
 header("Location: ../index.php?error=email");
 exit();
}

==
是比较运算符。要给任何变量赋值，只需使用single
=

<?php  
session_start();
include '../dbh.php';


if (isset($_POST['submit'])) {
    {$first = $_POST['first'];
    $last = $_POST['last'];
    $email = $_POST['email'];
    $pwd = $_POST['pwd'];

    $errorEmpty = false;
    $errorEmail = false;


if (empty($first) || empty($last) || empty($email) || empty($pwd)) {
 echo "<span class='form-error'>Please fill out all fields!</span>";
 $errorEmpty = true;
}

elseif (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
 echo "<span class='form-error'>Please enter a valid email address!</span>";
 $errorEmail = true;
} 


else {$sql = "SELECT email FROM user WHERE email='$email'";
$result = mysqli_query($conn, $sql);
$emailcheck = mysqli_num_rows($result);
}

if ($emailcheck > 0) {
 echo "Email address already exists";
 header("Location: ../index.php?error=email");
 exit();
}

检查赋值与相等运算符…检查赋值与相等运算符…我一直收到相同的错误。无论我把它们做成本地的还是全球的。我是否能够将变量定义为true或false？您是否检查了@t0mm13b所说的赋值运算符？检查了运算符。没有更多的错误，但仍然没有按预期工作，所以我想这是一个开始。非常感谢您的帮助。此$errorEmpty==false$errorEmail==false；应为$errorEmpty=false$errorEmail=false；我总是犯同样的错误。无论我把它们做成本地的还是全球的。我是否能够将变量定义为true或false？您是否检查了@t0mm13b所说的赋值运算符？检查了运算符。没有更多的错误，但仍然没有按预期工作，所以我想这是一个开始。非常感谢您的帮助。此$errorEmpty==false$errorEmail==false；应为$errorEmpty=false$errorEmail=false；