Build a Simple HTML Tetris Game: A Step-by-Step Guide

<p>Instructions for Creating a Simple HTML Tetris Game:</p>
<ol>
<li>
<p>Create an HTML document and open it in your favorite text editor.</p>
</li>
<li>
<p>Add the following HTML code to the document to create a basic structure:</p>
</li>
</ol>
<!DOCTYPE html>
<html>
  <head>
    <title>Tetris</title>
  </head>
  <body>
  </body>
</html>
<ol start="3">
<li>Within the body tag, add a canvas element where the game will be displayed:</li>
</ol>
<p><canvas id='tetris' width='200' height='400'></canvas></p>
<ol start="4">
<li>
<p>Create a JavaScript file and save it in the same folder as the HTML document.</p>
</li>
<li>
<p>Add a script tag to the HTML document and link it to the JavaScript file:</p>
</li>
</ol>
<script src='tetris.js'></script>
<ol start="6">
<li>Create variables for the canvas and context in the JavaScript file:</li>
</ol>
<p>let canvas = document.getElementById('tetris');
let context = canvas.getContext('2d');</p>
<ol start="7">
<li>Create a 2-dimensional array to represent the game board. Each element in the array will represent a single block on the board.</li>
</ol>
<p>let board = [
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
];</p>
<ol start="8">
<li>Add a function to draw the game board:</li>
</ol>
<p>function drawBoard() {
for (let r = 0; r &lt; board.length; r++) {
for (let c = 0; c &lt; board[r].length; c++) {
let x = c * 20;
let y = r * 20;
if (board[r][c] === 0) {
context.fillStyle = 'black';
context.fillRect(x, y, 20, 20);
}
}
}
}</p>
<ol start="9">
<li>Add a function to generate a random piece:</li>
</ol>
<p>function generatePiece() {
let piece = [
[0, 0, 0],
[1, 1, 1],
[0, 1, 0]
];</p>
<p>return piece;
}</p>
<ol start="10">
<li>Add a function to draw the piece on the game board:</li>
</ol>
<p>function drawPiece() {
let piece = generatePiece();
let x = 4;
let y = 0;</p>
<p>for (let r = 0; r &lt; piece.length; r++) {
for (let c = 0; c &lt; piece[r].length; c++) {
if (piece[r][c] === 1) {
context.fillStyle = 'red';
context.fillRect(x * 20, y * 20, 20, 20);
}
x++;
}
y++;
x = 4;
}
}</p>
<ol start="11">
<li>Add a function to move the piece down the board:</li>
</ol>
<p>function movePiece() {
let piece = generatePiece();
let y = 0;</p>
<p>for (let r = board.length - 1; r &gt;= 0; r--) {
for (let c = 0; c &lt; piece[r].length; c++) {
if (piece[r][c] === 1) {
board[y][c] = piece[r][c];
board[r][c] = 0;
}
}
y++;
}
}</p>
<ol start="12">
<li>Add a function to update the game board:</li>
</ol>
<p>function update() {
drawBoard();
drawPiece();
movePiece();
}</p>
<ol start="13">
<li>Add an event listener to call the update() function when the page loads:</li>
</ol>
<p>window.addEventListener('load', update);</p>
<ol start="14">
<li>Save the HTML and JavaScript files and open the HTML document in a browser to play the game.</li>
</ol>