How to Build a Sign-In Form with Password Strength Indicators

Introduction

In today’s digital world, building secure sign-in forms with password strength indicators is crucial. By providing users with real-time feedback about the strength of their passwords, you not only improve security but also enhance user experience. A password strength indicator shows users whether their password is weak, medium, or strong, based on various criteria such as length, complexity, and the inclusion of special characters. In this step-by-step guide, we’ll show you how to build a sign-in form with a password strength indicator using HTML, CSS, and JavaScript.

What is a Password Strength Indicator?

A password strength indicator is a tool that provides instant feedback to users about the strength of their passwords. As users type their password, the indicator visually displays whether the password meets certain security criteria, such as length, inclusion of numbers, uppercase and lowercase letters, and special characters. These indicators help users create stronger passwords, reducing the risk of security breaches.

Step-by-Step Guide to Building a Sign-In Form with Password Strength Indicators

1. Basic HTML Structure for the Sign-In Form

We’ll begin by creating a simple HTML structure that includes fields for a username, password, and the password strength indicator.


<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Sign-In Form with Password Strength Indicator</title>
  <link rel="stylesheet" href="styles.css">
</head>
<body>

  <div class="form-container">
    <form id="sign-in-form">
      <h2>Create Account</h2>

      <!-- Username Input -->
      <div class="input-group">
        <label for="username">Username</label>
        <input type="text" id="username" name="username" required>
      </div>

      <!-- Password Input and Strength Indicator -->
      <div class="input-group">
        <label for="password">Password</label>
        <input type="password" id="password" name="password" required>
        <div id="password-strength" class="strength-bar"></div>
        <small id="password-message"></small>
      </div>

      <button type="submit">Create Account</button>
    </form>
  </div>

  <script src="scripts.js"></script>
</body>
</html>

Explanation of the HTML Structure:

Form Layout:
- A basic sign-in form with fields for username and password.
- A password field followed by a password strength indicator (#password-strength), which will dynamically show password strength as the user types.
- A small message area (#password-message) is used to give additional feedback on password strength.

2. CSS for Styling the Form and Password Strength Indicator

Now, we’ll add some basic CSS to style the form and the password strength indicator. We’ll use different colors to indicate weak, medium, and strong passwords.


/* styles.css */

/* General Styling */
body, html {
  height: 100%;
  margin: 0;
  font-family: Arial, sans-serif;
  display: flex;
  justify-content: center;
  align-items: center;
  background-color: #f4f4f4;
}

.form-container {
  background-color: #fff;
  padding: 30px;
  border-radius: 10px;
  box-shadow: 0 4px 10px rgba(0, 0, 0, 0.1);
  width: 100%;
  max-width: 400px;
}

h2 {
  margin-bottom: 20px;
  text-align: center;
}

.input-group {
  margin-bottom: 20px;
}

label {
  display: block;
  margin-bottom: 5px;
  color: #333;
}

input {
  width: 100%;
  padding: 12px;
  border: 1px solid #ccc;
  border-radius: 5px;
  font-size: 16px;
}

button {
  width: 100%;
  padding: 12px;
  background-color: #007bff;
  color: white;
  border: none;
  border-radius: 5px;
  font-size: 16px;
  cursor: pointer;
}

button:hover {
  background-color: #0056b3;
}

/* Password Strength Indicator Styling */
.strength-bar {
  height: 10px;
  margin-top: 10px;
  border-radius: 5px;
  background-color: #e0e0e0;
}

.strength-bar.weak {
  background-color: #ff4b47;
}

.strength-bar.medium {
  background-color: #ffa500;
}

.strength-bar.strong {
  background-color: #4caf50;
}

#password-message {
  margin-top: 5px;
  font-size: 14px;
  color: #666;
}

Explanation of the CSS:

Form Styling:
- A clean, modern form layout with a white background, rounded corners, and a shadow to make it stand out from the page.
- The input fields are styled for readability and usability, and the submit button has a hover effect.
Password Strength Indicator:
- The .strength-bar shows the strength of the password, changing color based on the password’s complexity. It starts as a neutral gray and changes to red for weak, orange for medium, and green for strong passwords.
- The password message provides text-based feedback beneath the bar.

3. JavaScript for Real-Time Password Strength Evaluation

Next, we’ll add JavaScript to check the strength of the password in real time as the user types. The script will update the strength bar and the message based on the password’s complexity.


// scripts.js

const passwordInput = document.getElementById('password');
const strengthBar = document.getElementById('password-strength');
const passwordMessage = document.getElementById('password-message');

// Password Strength Evaluation
passwordInput.addEventListener('input', function() {
  const password = passwordInput.value;
  const strength = checkPasswordStrength(password);

  // Update the strength bar and message
  strengthBar.className = 'strength-bar';
  if (strength === 'weak') {
    strengthBar.classList.add('weak');
    passwordMessage.textContent = 'Weak password';
  } else if (strength === 'medium') {
    strengthBar.classList.add('medium');
    passwordMessage.textContent = 'Medium password';
  } else if (strength === 'strong') {
    strengthBar.classList.add('strong');
    passwordMessage.textContent = 'Strong password';
  }
});

// Function to Check Password Strength
function checkPasswordStrength(password) {
  let strength = 'weak';

  // Password strength criteria
  const hasUpperCase = /[A-Z]/.test(password);
  const hasLowerCase = /[a-z]/.test(password);
  const hasNumbers = /[0-9]/.test(password);
  const hasSpecialChars = /[!@#$%^&*(),.?":{}|<>]/.test(password);
  const isLongEnough = password.length >= 8;

  if (isLongEnough && hasUpperCase && hasLowerCase && hasNumbers && hasSpecialChars) {
    strength = 'strong';
  } else if (isLongEnough && (hasUpperCase || hasLowerCase) && hasNumbers) {
    strength = 'medium';
  }

  return strength;
}

Explanation of the JavaScript:

Real-Time Password Listener:
- The script listens for changes to the password field (passwordInput.addEventListener('input', ...)) and calls the checkPasswordStrength function to evaluate the password strength.
Password Strength Logic:
- The password is checked based on several criteria:
  - Length of at least 8 characters.
  - Presence of both uppercase and lowercase letters.
  - Inclusion of numbers and special characters.
- The password is classified as weak, medium, or strong based on how many of these criteria it meets.
Updating the Strength Bar and Message:
- The strength bar’s color is updated by changing its class to .weak, .medium, or .strong. The passwordMessage provides additional feedback, encouraging users to improve their passwords.

Best Practices for Building a Sign-In Form with Password Strength Indicators

When implementing a password strength indicator, consider the following best practices:

1. Set Clear Password Requirements

Clearly communicate the password requirements to the user. This can be done through placeholder text or an instruction section below the password field.


<small>Password must be at least 8 characters long and include uppercase letters, numbers, and special characters.</small>

2. Use Visual and Textual Feedback

In addition to color-coding the strength bar, use text-based feedback. This ensures that users understand why their password is classified as weak, medium, or strong.

3. Encourage Strong Passwords

Encourage users to create stronger passwords by suggesting improvements. If the password is too short or lacks complexity, prompt the user to add more characters or special symbols.

4. Make It Accessible

Ensure that your password strength indicator is accessible to all users, including those with disabilities. Use appropriate ARIA attributes and ensure that the color changes are not the only means of conveying information.


<input type="password" id="password" aria-label="Enter your password" required>

5. Ensure Security Best Practices

Always use HTTPS to ensure that data like passwords are encrypted when transmitted. Avoid storing passwords in plain text, and implement strong hashing algorithms like crypt for password storage.

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See the Pen How to Build a Sign-In Form with Password Strength Indicators by codepen (@codepen-the-selector) on CodePen.

Conclusion

Implementing a password strength indicator in your sign-in form not only improves security but also guides users toward creating stronger, more secure passwords. By providing real-time feedback, you can help users meet password complexity requirements and reduce the risk of security breaches. This step-by-step guide has shown you how to build a password strength indicator using HTML, CSS, and JavaScript, making it easier to create a secure sign-in process for your users.

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