In this exercise, you will be creating a Blackjack game. If you are unfamiliar with the rules of blackjack, please watch this video. Note that these instructions do not implement betting; only wins/losses.
You will make use of the following techniques:
- Selecting DOM elements using JavaScript
- Adding event listeners to DOM elements
- Creating new DOM Elements
- Setting DOM element Attributes
- Using template strings
- Loops (and nested loops)
- HTML and CSS
Follow the steps below to get started.
This project comes with some HTML and some JavaScript already included. Familiarise yourself with the HTML that is already there to see what DOM elements the browser will create when the document is loaded by the browser.
Style the page to make it look more like a card table. This exercise is less about styling, so do not spend more than 45-60 minutes on styling at this time. You can always revisit the styling later. Here is an example:
If you would rather get straight into the interactivity, you can find an example stylesheet in the extras folder. Simply link to that stylesheet from the head and move on to the next step.
To get an idea of what the cards will look like, we are going to "hard-code" them first, then you javascript to add the right card later. Start by adding the HTML for an img tag inside of the #dealer-hand or #player-hand element and have them link (set the src attribute) to card images in the images folder.
Now that we know what we want the HTML to look like, we can remove the cards we created in step 3. This time we will generate them dynamically using JavaScript. When the "Deal" button is clicked, deal 4 times. Once to the player, once to the dealer, then the player and then to the dealer.
We will need to attach an event listener to the button, create a new image element and append it to the #dealer-hand and the #player-hand elements. At this point, you can just use the same card.
When the "Hit" button is clicked, deal one more card to the player (use the same card image for now), and then another to the dealer.
Hint: Is there any code here that is repeated? Is there a way to use write a function to deal from the card to whichever player we chose?
The next step is to create a deck of cards. We can make our "deck" an array of objects. Each one of the objects in the deck will represent a card. Each card will have a rank and a suit. (N.B. the rank is NOT the same as points)
King of Hearts:
{ rank: 13, suit: 'hearts' }4 of Spades:
{ rank: 4, suit: 'spades' }Ace of Diamonds:
{ rank: 1, suit: 'diamonds' }Rather than manually code a whole deck of cards, we can write a function to generate a deck of 52 cards. Create a function buildDeck returns a new array with 52 card objects. There are 4 suits: diamonds, clubs, hearts and spades. For each suit there is a rank from 1 to 13.
Now that we have a deck of cards, we want to make use of it. We're going to need to create something to represent the player and dealer hands so go ahead and create two new arrays:
- dealerHand
- playerHand
These arrays of cards will later be used to calculate the total points for the hand.
Adjust the code so that when we click the "Deal" button, it will remove a card from the deck, then place that card into the playerHand array.
Hint: Is there an array method allows us to remove and return an item from an array?
Gameplay should still deal the same as before: 1 card each to player, dealer, player, dealer.
As you will have noticed, we have a whole folder of images with the following naming structure:
images/{rank}_of_{suit}.png
For example:
5_of_hearts.pngace_of_spades.pngjack_of_diamonds.png
In order to put a card visually on the page, we need to insert an tag, example:
<img src="/page/images/5_of_hearts.png" alt="5 of hearts" />Before, we were displaying images using the full, hard-coded URL for a specific card. Now we want to use the card objects to set the src attribute based on the card object.
Write a function getCardImage that will take a card object and return an image element containing the correct image URL for that card. As an example (this is not code you should use), the following code takes a single card and attaches the appropriate card image to the body of the page:
const card = { rank: 13, suit: 'hearts' };
const newCardImage = getCardImage(card)
document.body.append(newCardImage);Now that we have a way to create an image based on a card object, we need to display the player hand and the dealer hand on the page.
Write a function render that loops over the dealerHand and playerHand arrays and appends a new card image to the appropriate elements for each card in the hands.
Write a function to shuffle the deck. Here are some strategies for shuffling the deck:
- For fixed number of times, randomly choose 2 cards within the deck and swap them.
- Create a new array, randomly choose one card after another from the original array and push it to the new array.
- Search on StackOverflow for a solution to "shuffle a javascript array"
Use the shuffle function to shuffle the deck when you hit the deal button but before you deal the cards.
/**
* Randomize array element order in-place.
* Using Durstenfeld shuffle algorithm.
*/
function shuffleArray(array) {
for (var i = array.length - 1; i > 0; i--) {
var j = Math.floor(Math.random() * (i + 1));
var temp = array[i];
array[i] = array[j];
array[j] = temp;
}
return array;
}Write a function calculatePoints that takes in an array of card objects and returns the points for that hand. Example:
const playerHand = [
{ rank: 10, suit: 'diamonds' },
{ rank: 12, suit: 'spades'}
];
const playerPoints = calculatePoints(playerHand);
console.log(playerPoints);
// 20const playerHand = [
{ rank: 10, suit: 'diamonds' },
{ rank: 1, suit: 'clubs'}
];
const playerPoints = calculatePoints(playerHand);
console.log(playerPoints);
// 21After dealing any card, display the current points for the dealer and the player. You may want to consider adding this code to your render function.
Check for busts after each card is dealt. A bust is when either the dealer or the player's hand go over 21 points. When that happens, they lose. If there is a bust, display a message on the page saying that they busted. There is a div with an id of messages already on the page that you can use to do this.
When the "Stand" button is clicked, the player doesn't want any more cards. Deal cards to the dealer until he reaches 17 points or more.
When the dealer's turn is over, whoever has the most points wins. Determine the winner. Display a message to show who won. You might also want to disable the "Deal", "Hit", and "Stand" buttons at this point.
The last step is to be able to reset the game. What is involved with this? Is there code we can reuse? Is there a way to reset the dealer and player hands? What about the buttons? Do they need to be re-enabled? The messages?
If you complete all of the above functionality, you can choose one or more of these extra credit features to implement:
- Create a way to play the game with 3 decks of cards (156 cards) or six deck of cards (312 cards)
- Use an animation to reveal a card when it is drawn.
- Hide dealer's hole card, and reveal it before dealer's turn.
- Keep track of wins vs losses.
- Add betting structure instead of wins vs losses. The player with start out with a certain amount of money - say $500. There will be a minimum bet of $5. The player can choose an amount to bet before each hand.
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