html+js/formValidation.html

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Simple Form Validation</title>
    <style>
        form {
            width: 300px;
            margin: auto;
        }

        input {
            width: 100%;
            margin: 10px 0;
            padding: 8px;
        }

        .error {
            color: red;
            font-size: 12px;
        }
    </style>
</head>

<body>
    <h2 style="text-align: center;">Form Validation</h2>
    <form id="myForm" onsubmit="return validateForm()">
        <input type="text" id="name" placeholder="Name (A-Z)">
        <span class="error" id="nameError"></span>

        <input type="number" id="age" placeholder="Age (0-100)">
        <span class="error" id="ageError"></span>

        <input type="text" id="email" placeholder="Email (must contain @)">
        <span class="error" id="emailError"></span>

        <input type="password" id="password" placeholder="Password">
        <span class="error" id="passwordError"></span>

        <button type="submit">Submit</button>
    </form>

    <script>
        function validateForm() {
            const name = document.getElementById("name").value.trim();
            const age = document.getElementById("age").value.trim();
            const email = document.getElementById("email").value.trim();
            const password = document.getElementById("password").value.trim();

            const nameError = document.getElementById("nameError");
            const ageError = document.getElementById("ageError");
            const emailError = document.getElementById("emailError");
            const passwordError = document.getElementById("passwordError");

            // Clear previous error messages
            nameError.textContent = "";
            ageError.textContent = "";
            emailError.textContent = "";
            passwordError.textContent = "";

            let isValid = true;

            // Validate Name
            if (!/^[A-Za-z]+$/.test(name)) {
                nameError.textContent = "Name must only contain letters (A-Z).";
                isValid = false;
            }

            // Validate Age
            if (age === "" || age < 0 || age > 100) {
                ageError.textContent = "Age must be between 0 and 100.";
                isValid = false;
            }

            // Validate Email
            if (!email.includes("@")) {
                emailError.textContent = "Email must contain '@'.";
                isValid = false;
            }

            // Validate Password
            const passwordRegex = /^(?=.*[A-Z])(?=.*\d)(?=.*[@$!%*?&]).{6,}$/;
            if (!passwordRegex.test(password)) {
                passwordError.textContent =
                    "Password must include 1 uppercase letter, 1 number, 1 special character, and be at least 6 characters.";
                isValid = false;
            }

            return isValid;
        }
    </script>
</body>

</html>