php form的作用

<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
    $name = $_POST['name'];
    $email = $_POST['email'];
    // 处理数据...
}
?>
<form method="post" action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]);?>">
  Name: <input type="text" name="name">
  Email: <input type="text" name="email">
  <input type="submit">
</form>

<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
    $name = test_input($_POST["name"]);
    $email = test_input($_POST["email"]);

    if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
        echo "Invalid email format";
    }
}

function test_input($data) {
    $data = trim($data);
    $data = stripslashes($data);
    $data = htmlspecialchars($data);
    return $data;
}
?>
<form method="post" action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]);?>">
  Name: <input type="text" name="name">
  Email: <input type="text" name="email">
  <input type="submit">
</form>

<script>
function submitForm(event) {
    event.preventDefault();
    var formData = new FormData(document.getElementById('myForm'));
    fetch('submit.php', {
        method: 'POST',
        body: formData
    })
    .then(response => response.text())
    .then(result => console.log(result))
    .catch(error => console.error('Error:', error));
}
</script>
<form id="myForm" onsubmit="submitForm(event)">
  Name: <input type="text" name="name">
  Email: <input type="text" name="email">
  <input type="submit">
</form>