PHP를 사용하여 클라이언트 측 및 서버 측 양식 유효성 검사를 처리하는 방법

<form action="process.php" method="post" onsubmit="return validateForm()">
    <input type="text" id="name" name="name" placeholder="姓名">
    <span id="nameError" style="display: none;">请输入姓名</span>
    <br>
    <input type="email" id="email" name="email" placeholder="电子邮箱">
    <span id="emailError" style="display: none;">请输入有效的电子邮箱</span>
    <br>
    <input type="password" id="password" name="password" placeholder="密码">
    <span id="passwordError" style="display: none;">请输入密码</span>
    <br>
    <input type="submit" value="提交">
</form>

<script>
    function validateForm() {
        var name = document.getElementById("name").value;
        var email = document.getElementById("email").value;
        var password = document.getElementById("password").value;
        
        if (name === "") {
            document.getElementById("nameError").style.display = "block";
            return false;
        }
        
        if (email === "" || !email.includes("@")) {
            document.getElementById("emailError").style.display = "block";
            return false;
        }
        
        if (password === "") {
            document.getElementById("passwordError").style.display = "block";
            return false;
        }
        
        return true;
    }
</script>

<?php
if ($_SERVER["REQUEST_METHOD"] === "POST") {
    $name = $_POST["name"];
    $email = $_POST["email"];
    $password = $_POST["password"];
    
    $errors = [];
    
    if ($name === "") {
        $errors[] = "请输入姓名";
    }
    
    if ($email === "" || !filter_var($email, FILTER_VALIDATE_EMAIL)) {
        $errors[] = "请输入有效的电子邮箱";
    }
    
    if ($password === "") {
        $errors[] = "请输入密码";
    }
    
    if (count($errors) > 0) {
        // 打印错误信息
        foreach ($errors as $error) {
            echo $error . "<br>";
        }
    } else {
        // 对表单数据进行进一步处理
        // ...
        echo "表单验证通过，数据已提交";
    }
}
?>