DEV Community πŸ‘©β€πŸ’»πŸ‘¨β€πŸ’»

Michael Burrows
Michael Burrows

Posted on • Updated on • Originally published at michaelburrows.xyz

Create a random playing card generator with JavaScript

In this tutorial we’ll be using JavaScript to generate a deck of playing cards and then select a random card from that deck. We’ll then output the random card in the browser and add some CSS so it looks like an actual playing card. If you’re interested in building card games using JavaScript this is a good starting point before moving onto more elaborate games.

Let’s get started by creating a index.html file with the following markup:

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <title>Random Playing Card</title>
    <link rel="stylesheet" href="style.css" />
  </head>
  <body>    
    <script src="script.js"></script>
  </body>
</html>
Enter fullscreen mode Exit fullscreen mode

Then create a script.js file and add a deckBuilder function that we’ll use to generate an array containing the values for 52 playing cards:

function deckBuilder() {
  // ...
}
Enter fullscreen mode Exit fullscreen mode

Inside deckBuilder define the values and suits used in a deck of playing cards:

const values = [ "A", "2", "3", "4", "5", "6", "7", "8", "9", "10", "J", "Q", "K", ];
const suits = ["Hearts", "Diamonds", "Spades", "Clubs"];
Enter fullscreen mode Exit fullscreen mode

Next loop through the suits array whilst also looping through the values array and push the combined data into the cards array:

const cards = [];
for (let s = 0; s < suits.length; s++) {
  for (let v = 0; v < values.length; v++) {
    const value = values[v];
    const suit = suits[s];
    cards.push({ value, suit });
  }
}
return cards;
Enter fullscreen mode Exit fullscreen mode

We now have a function that creates an array with the suit/value combination for 52 playing cards structured as follows:

0: {value: "A", suit: "Hearts"}
1: {value: "2", suit: "Hearts"}
2: {value: "3", suit: "Hearts"}
Enter fullscreen mode Exit fullscreen mode

Next we’ll create the randomCard function passing it the cards array:

function randomCard(cards) { 
  // ...
}
const cards = deckBuilder();
randomCard(cards);
Enter fullscreen mode Exit fullscreen mode

Inside the randomCard function we’ll generate a random number between 0 and 51 (not 52 as array indexes start at 0) and get the data from the cards array at that index. This data is then stored in variables to make it easier to work with later:

const random = Math.floor(Math.random() * 51);  
const cardValue = cards[random].value;
const cardSuit = cards[random].suit;
Enter fullscreen mode Exit fullscreen mode

As there are HTML character entities for each of the playing card suits (β™₯/♦/β™ /♣) we can output these onto our playing card without having to use images. Because the entity code for diamonds is truncated we need to also truncate the "Diamonds" string, the other suits entity codes match the strings (&hearts; &spades; &clubs;) so all we need todo is convert them to lowercase.

let entity;
cardSuit === "Diamonds" ? (entity = "&diams;") : (entity = "&" + cardSuit.toLowerCase() + ";");
Enter fullscreen mode Exit fullscreen mode

Finally we can render the random card into the HTML page. If you look at the final design for this project you’ll see why cardValue and entity have been repeated.

const card = document.createElement("div");
card.classList.add("card", cardSuit.toLowerCase());
card.innerHTML = 
'<span class="card-value-suit top">' + cardValue + entity + '</span>' + 
'<span class="card-suit">' + entity + '</span>' + 
'<span class="card-value-suit bot">' + cardValue + entity + '</span>';
document.body.appendChild(card);
Enter fullscreen mode Exit fullscreen mode

With the functionality complete we can add some CSS to our random playing card.

Create a file called style.css and add the following to create the basic playing card shape:

.card {  
  position: relative;
  width: 105px;
  height: 150px;
  border-radius: 5px;
  border: 1px solid #ccc;
  box-shadow: 0px 0px 5px 0px rgba(0,0,0,0.25);
}
Enter fullscreen mode Exit fullscreen mode

Because .card is positioned relatively we can use absolute positioning for the top and bottom text. We’ll also rotate the text at the bottom 180 degrees just like a real playing card.

.card-value-suit {
  display: inline-block;
  position: absolute;
}
.card-value-suit.top {
  top: 5px;
  left: 5px;
}
.card-value-suit.bot {
  transform: rotate(180deg);
  bottom: 5px;
  right: 5px;
}
.card-suit {
  font-size: 50px;
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  left: 25%;
}
Enter fullscreen mode Exit fullscreen mode

And finally we’ll add the colors for each of the suits:

.card.spades,
.card.clubs {
  color: black;
}
.card.hearts,
.card.diamonds {
  color: red;
}
Enter fullscreen mode Exit fullscreen mode

Top comments (1)

Collapse
 
divyesh_golani profile image
DivyeshGolani

Nice one!

Here is a post you might want to check out:

Regex for lazy developers

regex for lazy devs

Sorry for the callout πŸ˜†