如何以特定方式展示密码输入及重复验证的错误信息？

First, let's fix and complete your incomplete HTML code, adding dedicated containers to hold validation error messages for both password fields:

<!DOCTYPE html>
<html>
<head>
    <style>
        /* Basic styling for error messages and form elements */
        .error-message {
            color: #dc3545;
            font-size: 0.875em;
            margin-top: 0.25rem;
            display: none;
        }
        .red-star {
            color: #dc3545;
            margin-left: 0.25rem;
        }
        .needContent {
            margin-bottom: 1.25rem;
            display: flex;
            flex-direction: column;
        }
        label {
            margin-bottom: 0.5rem;
        }
    </style>
</head>
<body>
    <div class="needContent">
        <label for="Password">Password</label>
        <span class="red-star">&lowast;</span>
        <input type="password" name="Password" id="Password" required="required" 
               onkeyup="validatePassword()" onchange="validatePassword()"
               pattern="^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)[a-zA-Z\d]{8,}$">
        <div id="password-error" class="error-message"></div>
    </div>
    <div class="needContent">
        <label for="Retype_Password">Retype Password</label>
        <span class="red-star">&lowast;</span>
        <input type="password" name="Retype_Password" id="Retype_Password" required="required"
               onkeyup="validateRetypePassword()" onchange="validateRetypePassword()">
        <div id="retype-password-error" class="error-message"></div>
    </div>

    <script>
        // Validate password against the required pattern
        function validatePassword() {
            const passwordInput = document.getElementById('Password');
            const errorElement = document.getElementById('password-error');
            
            if (!passwordInput.validity.valid) {
                if (passwordInput.validity.valueMissing) {
                    errorElement.textContent = 'Password is required.';
                } else if (passwordInput.validity.patternMismatch) {
                    errorElement.textContent = 'Password must be at least 8 characters, include one uppercase letter, one lowercase letter, and one number.';
                }
                errorElement.style.display = 'block';
            } else {
                errorElement.style.display = 'none';
                // Trigger retype validation automatically when password is valid
                validateRetypePassword();
            }
        }

        // Validate retyped password matches the original
        function validateRetypePassword() {
            const password = document.getElementById('Password').value;
            const retypePassword = document.getElementById('Retype_Password').value;
            const errorElement = document.getElementById('retype-password-error');
            
            if (retypePassword === '') {
                errorElement.textContent = 'Please retype your password.';
                errorElement.style.display = 'block';
            } else if (password !== retypePassword) {
                errorElement.textContent = 'Passwords do not match.';
                errorElement.style.display = 'block';
            } else {
                errorElement.style.display = 'none';
            }
        }
    </script>
</body>
</html>

Key Details Breakdown: #

• Error Message Containers: We added <div> elements with class error-message below each input. These are hidden by default and only show when validation fails.
• Real-Time Feedback: Using onkeyup and onchange events triggers validation as the user types or moves away from the field, so they get immediate feedback instead of waiting to submit the form.
• Specific Error Messages: Instead of generic alerts, we show targeted messages for each failure case (empty field, pattern mismatch, password mismatch) to guide the user clearly.
• Fixed Regex: I corrected your original pattern attribute—you had escaped brackets (\[a-z\]) which would literally match brackets in the password; it should be [a-z] without escapes to match lowercase letters.

内容的提问来源于stack exchange，提问作者Amina