Creating a game using events

Have you ever wondered how websites know when you click a button or type in a text box? That's the magic of event-driven programming! What better way to learn this essential skill than by building something useful - a typing speed game that reacts to every keystroke you make. You're going to see firsthand how web browsers "talk" to your JavaScript code. Every time you click, type, or move your mouse, the browser is sending little messages (we call them events) to your code, and you get to decide how to respond! By the time we're done here, you'll have built a real typing game that tracks your speed and accuracy. More importantly, you'll understand the fundamental concepts that power every interactive website you've ever used. Let's dive in! ## Pre-Lecture Quiz Pre-lecture quiz ## Event driven programming Think about your favorite app or website - what makes it feel alive and responsive? It's all about how it reacts to what you do! Every tap, click, swipe, or keystroke creates what we call an "event," and that's where the real magic of web development happens. Here's what makes programming for the web so interesting: we never know when someone will click that button or start typing in a text box. They might click immediately, wait five minutes, or maybe never click at all! This unpredictability means we need to think differently about how we write our code. Instead of writing code that runs from top to bottom like a recipe, we write code that sits patiently waiting for something to happen. It's similar to how telegraph operators in the 1800s would sit by their machines, ready to respond the moment a message came through the wire. So what exactly is an "event"? Simply put, it's something that happens! When you click a button - that's an event. When you type a letter - that's an event. When you move your mouse - that's another event. Event-driven programming lets us set up our code to listen and respond. We create special functions called event listeners that wait patiently for specific things to happen, then spring into action when they do. Think of event listeners like having a doorbell for your code. You set up the doorbell (addEventListener()), tell it what sound to listen for (like a 'click' or 'keypress'), and then specify what should happen when someone rings it (your custom function). Here's how event listeners work: - Listens for specific user actions like clicks, keystrokes, or mouse movements - Executes your custom code when the specified event occurs - Responds immediately to user interactions, creating a seamless experience - Handles multiple events on the same element using different listeners ### Common events While web browsers offer dozens of different events you can listen for, most interactive applications rely on just a handful of essential events. Understanding these core events will give you the foundation to build sophisticated user interactions. There are dozens of events available for you to listen to when creating an application. Basically anything a user does on a page raises an event, which gives you a lot of power to ensure they get the experience you desire. Fortunately, you'll normally only need a small handful of events. Here's a few common ones (including the two we'll use when creating our game): Understanding these event types: - Triggers when users interact with specific elements on your page - Provides detailed information about the user's action through event objects - Enables you to create responsive, interactive web applications - Works consistently across different browsers and devices ## Creating the game Now that you understand how events work, let's put that knowledge into practice by building something useful. We'll create a typing speed game that demonstrates event handling while helping you develop an important developer skill. We're going to create a game to explore how events work in JavaScript. Our game will test a player's typing skill, which is one of the most underrated skills all developers should have. Fun fact: the QWERTY keyboard layout we use today was actually designed in the 1870s for typewriters - and good typing skills are still just as valuable for programmers today! The general flow of the game will look like this: Here's how our game will work: - Starts when the player clicks the start button and displays a random quote - Tracks the player's typing progress word by word in real-time - Highlights the current word to guide the player's focus - Provides immediate visual feedback for typing errors - Calculates and displays the total time when the quote is completed Let's build our game, and learn about events! ### File structure Before we start coding, let's get organized! Having a clean file structure from the beginning will save you headaches later and make your project more professional. 😊 We're going to keep things simple with just three files: index.html for our page structure, script.js for all our game logic, and style.css to make everything look great. This is the classic trio that powers most of the web! Create a new folder for your work by opening a console or terminal window and issuing the following command: Here's what these commands do: - Creates a new directory called typing-game for your project files - Navigates into the newly created directory automatically - Sets up a clean workspace for your game development Open Visual Studio Code: This command: - Launches Visual Studio Code in the current directory - Opens your project folder in the editor - Provides access to all the development tools you'll need Add three files to the folder in Visual Studio Code with the following names: - index.html - Contains the structure and content of your game - script.js - Handles all the game logic and event listeners - style.css - Defines the visual appearance and styling ## Create the user interface Now let's build the stage where all our game action will happen! Think of this like designing the control panel for a spaceship - we need to make sure everything our players need is right where they expect it to be. Let's figure out what our game actually needs. If you were playing a typing game, what would you want to see on the screen? Here's what we'll need: Understanding the UI structure: - Organizes content logically from top to bottom - Assigns unique IDs to elements for JavaScript targeting - Provides clear visual hierarchy for better user experience - Includes semantic HTML elements for accessibility Each of those will need IDs so we can work with them in our JavaScript. We will also add references to the CSS and JavaScript files we're going to create. Create a new file named index.html. Add the following HTML: Breaking down what this HTML structure accomplishes: - Links the CSS stylesheet in the for styling - Creates a clear heading and instructions for users - Establishes placeholder paragraphs with specific IDs for dynamic content - Includes an input field with accessibility attributes - Provides a start button to trigger the game - Loads the JavaScript file at the end for optimal performance ### Launch the application Testing your application frequently during development helps you catch issues early and see your progress in real-time. Live Server is an invaluable tool that automatically refreshes your browser whenever you save changes, making development much more efficient. It's always best to develop iteratively to see how things look. Let's launch our application. There's a wonderful extension for Visual Studio Code called Live Server which will both host your application locally and refresh the browser each time you save. Install Live Server by following the link and clicking Install: Here's what happens during installation: - Prompts your browser to open Visual Studio Code - Guides you through the extension installation process - May require restarting Visual Studio Code to complete setup Once installed, in Visual Studio Code, click Ctrl-Shift-P (or Cmd-Shift-P) to open the command palette: Understanding the command palette: - Provides quick access to all VS Code commands - Searches commands as you type - Offers keyboard shortcuts for faster development Type "Live Server: Open with Live Server": What Live Server does: - Starts a local development server for your project - Automatically refreshes the browser when you save files - Serves your files from a local URL (typically localhost:5500) Open a browser and navigate to https://localhost:5500: You should now see the page you created! Let's add some functionality. ## Add the CSS Now let's make things look good! Visual feedback has been crucial for user interfaces since the early days of computing. In the 1980s, researchers discovered that immediate visual feedback dramatically improves user performance and reduces errors. That's exactly what we're going to create. Our game needs to be crystal clear about what's happening. Players should immediately know which word they're supposed to type, and if they make a mistake, they should see it right away. Let's create some simple but effective styling: Create a new file named style.css and add the following syntax. Understanding these CSS classes: - Highlights the current word with a yellow background for clear visual guidance - Signals typing errors with a light coral background color - Provides immediate feedback without disrupting the user's typing flow - Uses contrasting colors for accessibility and clear visual communication ✅ When it comes to CSS you can layout your page however you might like. Take a little time and make the page look more appealing: - Choose a different font - Colorize the headers - Resize items ## JavaScript Here's where things get interesting! 🎉 We've got our HTML structure and our CSS styling, but right now our game is like a beautiful car without an engine. JavaScript is going to be that engine - it's what makes everything actually work and respond to what players do. This is where you'll see your creation come to life. We're going to tackle this step by step so nothing feels overwhelming: This structured approach helps you: - Organize your code into logical, manageable sections - Build functionality incrementally for easier debugging - Understand how different parts of your application work together - Create reusable patterns for future projects But first, create a new file named script.js. ### Add the constants Before we dive into the action, let's gather all our resources! Just like how NASA mission control sets up all their monitoring systems before launch, it's much easier when you have everything prepared and ready to go. This saves us from hunting around for things later and helps prevent typos. Here's what we need to set up first: We'll also need references to our UI elements: Breaking down what this setup code accomplishes: - Stores an array of Sherlock Holmes quotes using const since the quotes won't change - Initializes tracking variables with let since these values will update during gameplay - Captures references to DOM elements using document.getElementById() for efficient access - Sets up the foundation for all game functionality with clear, descriptive variable names - Organizes related data and elements logically for easier code maintenance ✅ Go ahead and add more quotes to your game Here's why this approach works so well: - Prevents spelling errors when referencing elements multiple times - Improves code readability with descriptive constant names - Enables better IDE support with autocomplete and error checking - Makes refactoring easier if element IDs change later Take a minute to watch a video on using const, let and var ### Add start logic This is where everything clicks into place! 🚀 You're about to write your first real event listener, and there's something quite satisfying about seeing your code respond to a button click. Think about it: somewhere out there, a player is going to click that "Start" button, and your code needs to be ready for them. We have no idea when they'll click it - could be immediately, could be after they grab a coffee - but when they do, your game springs to life. When the user clicks start, we need to select a quote, setup the user interface, and setup tracking for the current word and timing. Below is the JavaScript you'll need to add; we discuss it just after the script block. Let's break down the code into logical sections: 📊 Word Tracking Setup: - Selects a random quote using Math.floor() and Math.random() for variety - Converts the quote into an array of individual words using split(' ') - Resets the wordIndex to 0 since players start with the first word - Prepares the game state for a fresh round 🎨 UI Setup and Display: - Creates an array of elements, wrapping each word for individual styling - Joins the span elements into a single string for efficient DOM updating - Highlights the first word by adding the highlight CSS class - Clears any previous game messages to provide a clean slate ⌨️ Textbox Preparation: - Clears any existing text in the input field - Sets focus to the textbox so players can start typing immediately - Prepares the input area for the new game session ⏱️ Timer Initialization: - Captures the current timestamp using new Date().getTime() - Enables accurate calculation of typing speed and completion time - Starts the performance tracking for the game session ### Add typing logic Here's where we tackle the heart of our game! Don't worry if this seems like a lot at first - we'll walk through every piece, and by the end, you'll see how logical it all is. What we're building here is quite sophisticated: every single time someone types a letter, our code is going to check what they typed, give them feedback, and decide what should happen next. It's similar to how early word processors like WordStar in the 1970s provided real-time feedback to typists. Understanding the typing logic flow: This function uses a waterfall approach, checking conditions from most specific to most general. Let's break down each scenario: 🏁 Quote Complete (Scenario 1): - Checks if typed value matches current word AND we're on the last word - Calculates elapsed time by subtracting start time from current time - Converts milliseconds to seconds by dividing by 1,000 - Displays congratulatory message with completion time ✅ Word Complete (Scenario 2): - Detects word completion when input ends with a space - Validates that trimmed input matches the current word exactly - Clears the input field for the next word - Advances to the next word by incrementing wordIndex - Updates visual highlighting by removing all classes and highlighting the new word 📝 Typing in Progress (Scenario 3): - Verifies that the current word starts with what's been typed so far - Removes any error styling to show the input is correct - Allows continued typing without interruption ❌ Error State (Scenario 4): - Triggers when typed text doesn't match the expected word beginning - Applies error CSS class to provide immediate visual feedback - Helps players quickly identify and correct mistakes ## Test your application Look what you've accomplished! 🎉 You just built a real, working typing game from scratch using event-driven programming. Take a moment to appreciate that - this is no small feat! Now comes the testing phase! Will it work as expected? Did we miss something? Here's the thing: if something doesn't work perfectly right away, that's completely normal. Even experienced developers find bugs in their code regularly. It's all part of the development process! Click on start, and start typing away! It should look a little like the animation we saw before. What to test in your application: - Verifies that clicking Start displays a random quote - Confirms that typing highlights the current word correctly - Checks that error styling appears for incorrect typing - Ensures that completing words advances the highlight properly - Tests that finishing the quote shows the completion message with timing Common debugging tips: - Check the browser console (F12) for JavaScript errors - Verify that all file names match exactly (case-sensitive) - Ensure Live Server is running and refreshing properly - Test different quotes to verify the random selection works --- ## GitHub Copilot Agent Challenge 🎮 Use the Agent mode to complete the following challenge: Description: Extend the typing game by implementing a difficulty system that adjusts the game based on player performance. This challenge will help you practice advanced event handling, data analysis, and dynamic UI updates. Prompt: Create a difficulty adjustment system for the typing game that: 1. Tracks the player's typing speed (words per minute) and accuracy percentage 2. Automatically adjusts to three difficulty levels: Easy (simple quotes), Medium (current quotes), Hard (complex quotes with punctuation) 3. Displays the current difficulty level and player statistics on the UI 4. Implements a streak counter that increases difficulty after 3 consecutive good performances 5. Adds visual feedback (colors, animations) to indicate difficulty changes Add the necessary HTML elements, CSS styles, and JavaScript functions to implement this feature. Include proper error handling and ensure the game remains accessible with appropriate ARIA labels. Learn more about agent mode here. ## 🚀 Challenge Ready to take your typing game to the next level? Try implementing these advanced features to deepen your understanding of event handling and DOM manipulation: Add more functionality: Implementation tips: - Research localStorage.setItem() and localStorage.getItem() for persistent storage - Practice adding and removing event listeners dynamically - Explore HTML dialog elements or CSS modal patterns - Consider accessibility when disabling and enabling form controls ## Post-Lecture Quiz Post-lecture quiz --- ## 🚀 Your Typing Game Mastery Timeline ### ⚡ What You Can Do in the Next 5 Minutes - [ ] Test your typing game with different quotes to ensure it works smoothly - [ ] Experiment with the CSS styling - try changing the highlight and error colors - [ ] Open your browser's DevTools (F12) and watch the Console while playing - [ ] Challenge yourself to complete a quote as fast as possible ### ⏰ What You Can Accomplish This Hour - [ ] Add more quotes to the array (maybe from your favorite books or movies) - [ ] Implement the localStorage high score system from the challenge section - [ ] Create a words-per-minute calculator that displays after each game - [ ] Add sound effects for correct typing, errors, and completion ### 📅 Your Week-Long Adventure - [ ] Build a multiplayer version where friends can compete side-by-side - [ ] Create different difficulty levels with varying quote complexity - [ ] Add a progress bar showing how much of the quote is complete - [ ] Implement user accounts with personal statistics tracking - [ ] Design custom themes and let users choose their preferred styling ### 🗓️ Your Month-Long Transformation - [ ] Create a typing course with lessons that progressively teach proper finger placement - [ ] Build analytics that show which letters or words cause the most errors - [ ] Add support for different languages and keyboard layouts - [ ] Integrate with educational APIs to pull quotes from literature databases - [ ] Publish your enhanced typing game for others to use and enjoy ### 🎯 Final Reflection Check-in Before you move on, take a moment to celebrate: - What was the most satisfying moment while building this game? - How do you feel about event-driven programming now compared to when you started? - What's one feature you're excited to add to make this game uniquely yours? - How might you apply event handling concepts to other projects? --- ## Review & Self Study Read up on all the events available to the developer via the web browser, and consider the scenarios in which you would use each one. ## Assignment Create a new keyboard game