How to Preserve User-Selected Themes in a JavaScript Quiz

Why Your Quiz Theme Keeps Resetting (and How to Fix It)

When creating an interactive web quiz, user customization adds a personal touch that enhances the experience. In your Harry Potter-themed quiz, the ability to switch between house themes, like Slytherin or Gryffindor, is a great feature. However, you may have encountered a common problem: the theme resets after each question, leaving users frustrated.

This issue occurs because the current theme isn't saved properly between question loads. Without a way to remember the user's choice, the default settings are applied each time a new question is displayed. It’s essential to fix this so users feel immersed in their chosen house as they progress through the quiz.

Fortunately, JavaScript provides ways to store the user’s selected theme using browser storage methods like localStorage or session variables. By implementing this solution, you can ensure the theme stays consistent as users move through the quiz. This way, the personalized experience remains uninterrupted.

In this guide, we will walk through how to save the selected theme using JavaScript. By the end, your quiz will preserve the user's choice throughout the session, giving them a seamless experience. Let's dive into the solution!

How to Save User-Selected Themes in a Dynamic Quiz

The JavaScript scripts provided above are designed to solve the issue of retaining a user-selected theme in a quiz. This is particularly important in interactive quizzes, like the one themed around the Harry Potter universe, where users can switch between house themes such as Slytherin, Gryffindor, or Hufflepuff. Without proper handling, the selected theme resets every time the user answers a question and the next one is displayed. The main goal of these scripts is to ensure that once a user selects a theme, it is consistently applied throughout the quiz.

One solution involves using localStorage or sessionStorage, both of which are storage mechanisms provided by modern browsers. LocalStorage allows you to store the selected theme permanently, meaning it will still be available even if the page is refreshed or the browser is closed. The theme is saved by setting it in localStorage whenever the user selects a house, and then retrieving that saved theme when the page loads again. SessionStorage, on the other hand, works similarly but only saves data for the duration of the current session. Once the session ends, the data is lost, making it more temporary.

Another method involves manipulating the URL parameters. This solution is helpful when you want the theme to be reflected in the URL, allowing users to share links that retain the selected theme. This method uses JavaScript to append the chosen theme as a parameter in the URL and retrieves it upon page load. By modifying the browser's URL with the current theme, this approach ensures that the user can directly load a specific theme whenever they return to the quiz using that link. This can also be helpful for creating sharable links that retain the theme information.

Each of these methods, whether it’s using localStorage, sessionStorage, or URL parameters, addresses the main challenge of preserving user settings. It enhances the overall user experience by maintaining the desired customization throughout the interaction with the quiz. The scripts also include modular functions like resetTheme and applyClass, ensuring that the code remains organized, reusable, and easy to maintain. These functions handle the removal and addition of CSS classes to update the page appearance, making sure that the selected theme is properly applied every time.

// Function to save the theme to localStorage
function saveTheme(theme) {
  localStorage.setItem('selectedTheme', theme);
}

// Function to apply the saved theme
function applyTheme() {
  const savedTheme = localStorage.getItem('selectedTheme');
  if (savedTheme) {
    document.querySelectorAll('.customizable').forEach(element => {
      element.classList.add(savedTheme);
    });
  }
}

// Function to handle theme change
function popUp() {
  document.querySelector('#Serpentard').addEventListener('click', () => {
    resetTheme();
    applyClass('Serpentard');
    saveTheme('Serpentard');
  });

  // Similar logic for other house buttons
}

// Call the applyTheme function on page load
window.onload = applyTheme;

// Function to save the theme to sessionStorage
function saveThemeSession(theme) {
  sessionStorage.setItem('selectedTheme', theme);
}

// Function to apply the saved theme
function applyThemeSession() {
  const savedTheme = sessionStorage.getItem('selectedTheme');
  if (savedTheme) {
    document.querySelectorAll('.customizable').forEach(element => {
      element.classList.add(savedTheme);
    });
  }
}

// Function to handle theme change
function popUp() {
  document.querySelector('#Serpentard').addEventListener('click', () => {
    resetTheme();
    applyClass('Serpentard');
    saveThemeSession('Serpentard');
  });

  // Similar logic for other house buttons
}

// Call the applyTheme function on page load
window.onload = applyThemeSession;

// Function to get URL parameter
function getParameterByName(name) {
  const url = new URL(window.location.href);
  return url.searchParams.get(name);
}

// Function to apply theme from URL
function applyThemeFromURL() {
  const theme = getParameterByName('theme');
  if (theme) {
    document.querySelectorAll('.customizable').forEach(element => {
      element.classList.add(theme);
    });
  }
}

// Event listener to append theme to URL when selected
function popUp() {
  document.querySelector('#Serpentard').addEventListener('click', () => {
    resetTheme();
    applyClass('Serpentard');
    window.history.replaceState({}, '', '?theme=Serpentard');
  });

  // Similar logic for other house buttons
}

// Apply theme based on URL parameter
window.onload = applyThemeFromURL;

Ensuring Theme Persistence in JavaScript-Based Web Quizzes

One important aspect of creating a seamless user experience in dynamic web applications, such as a quiz, is ensuring that the settings a user selects, like a theme, are preserved across page refreshes or changes. In the context of your Harry Potter-themed quiz, this means making sure the chosen house (e.g., Slytherin or Gryffindor) is retained as users move through the quiz. This issue can arise because JavaScript functions, unless specifically programmed, do not retain state once a page reloads or moves to another section.

An additional way to solve this problem is by using cookies to store the selected theme. Cookies, like localStorage, allow for storing data in the user's browser, but they offer more flexibility in terms of expiration time and are sent to the server with every request. In a quiz application where user preferences like themes are important, storing these preferences in cookies can ensure persistence even if the user returns later. This is particularly useful when a long-term session is desired.

Another method to consider is leveraging modern front-end frameworks like React or Vue.js. These frameworks offer built-in state management tools that can store and maintain the state of the quiz, including the chosen theme. By handling state within the component architecture of these frameworks, you can make sure that user selections are maintained without having to write extensive custom logic. State persistence is key for keeping the quiz responsive and engaging for users, ensuring their preferences are respected.