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Design a login form using HTML & JavaScript with following validations usingRegular Expression on username and password fields.1. Username and Password should not be both blank2. Username should not start with digit,_, @ or #3. Password length must be 8 to 16 characters

Question

Design a login form using HTML & JavaScript with following validations usingRegular Expression on username and password fields.1. Username and Password should not be both blank2. Username should not start with digit,_, @ or #3. Password length must be 8 to 16 characters

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Solution

Sure, here is a simple example of a login form using HTML and JavaScript with the specified validations:

HTML:

<!DOCTYPE html>
<html>
<head>
    <title>Login Form</title>
</head>
<body>
    <form id="loginForm">
        <label for="username">Username:</label><br>
        <input type="text" id="username" name="username"><br>
        <label for="password">Password:</label><br>
        <input type="password" id="password" name="password"><br>
        <input type="submit" value="Submit">
    </form>
    <p id="error"></p>
</body>
</html>

JavaScript:

document.getElementById('loginForm').addEventListener('submit', function(event) {
    event.preventDefault();

    var username = document.getElementById('username').value;
    var password = document.getElementById('password').value;
    var error = document.getElementById('error');

    // Check if username and password are not blank
    if (username === '' || password === '') {
        error.textContent = 'Username and Password should not be blank.';
        return;
    }

    // Check if username starts with digit, _, @ or #
    if (/^[0-9_@#]/.test(username)) {
        error.textContent = 'Username should not start with digit, _, @ or #.';
        return;
    }

    // Check if password length is between 8 and 16 characters
    if (password.length < 8 || password.length > 16) {
        error.textContent = 'Password length must be 8 to 16 characters.';
        return;
    }

    // If all validations pass, clear the error message
    error.textContent = '';
    alert('Login successful!');
});

This code creates a simple form with username and password fields. When the form is submitted, it checks the following:

  1. If either the username or password is blank, it displays an error message.
  2. If the username starts with a digit, _, @, or #, it displays an error message.
  3. If the password is not between 8 and 16 characters, it displays an error message.

If all these checks pass, it clears the error message and displays a success message.

This problem has been solved

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