Generating a maze with Javascript & Canvas

Generating a maze with Javascript & Canvas - javascript

I'm having a peculiar issue with a maze generation program I'm writing for my resume. I'm using canvas and the entire thing works perfectly, except it won't draw the square correctly in the end.
It works by using this object template:
{row:nRow,
col:nCol,
visited:false,
left:true,
right:true,
top:true,
bottom:true};
And I use a depth first search to generate the maze. To break the walls, I detect where the neighbor is relative to the current tile and I shut the walls between them off.
For example, if I'm breaking a neighbor to the north, I'd do the following:
currentTile.top = false;
neighbor.bottom = false;
I triple checked with the google console and this part works fine. However, when I redraw it using the canvas, it doesn't remove the walls correctly, it looks like this:
Code from GitHub:
var canvas;
var ctx;
var tiles = [];
var visitedStk = [];
init();
function createPoint(nRow, nCol) {
/*Cell class*/
var obj = {
row: nRow,
col: nCol,
visited: false,
left: true,
right: true,
top: true,
bottom: true
};
return obj;
}
function init() {
/*Initialize needed variables. */
$("#newMazeBtn").click(reDrawMaze);
canvas = $("#mazeCanvas")[0];
ctx = canvas.getContext("2d");
drawBase();
}
function drawLine(sX, sY, eX, eY) {
/*Draw a line from the starting X and Y positions to the ending X and Y positions*/
ctx.moveTo(sX, sY);
ctx.lineTo(eX, eY);
}
function drawCell(x, y, side, tile) {
/* Draw cell based on wall properties */
var left = tile.left;
var right = tile.right;
var top = tile.top;
var bottom = tile.bottom;
var size = 25;
ctx.beginPath();
if (left) {
drawLine(x, y, x, y + size);
}
if (right) {
drawLine(x + size, y, x + size, y + size);
}
if (bottom) {
drawLine(x, y + size, x + size, y + size)
}
if (top) {
drawLine(x, y, x + size, y);
}
ctx.stroke();
}
function drawBase() {
/* Draw the tiles on the canvas*/
var side = 25;
for (var i = 0; i < 10; i++) {
tiles[i] = [];
for (var j = 0; j < 10; j++) {
tiles[i].push(createPoint(i, j));
drawCell(i * side, j * side, side, tiles[i][j]);
}
}
generateMaze(0, 0);
}
function clearCanvas() {
ctx.clearRect(0, 0, canvas.width, canvas.height);
}
function redrawTiles() {
var currentTile;
clearCanvas();
var side = 25;
for (var i = 0; i < 10; i++) {
for (var j = 0; j < 10; j++) {
currentTile = tiles[i][j];
drawCell(i * side, j * side, side, currentTile);
}
}
}
function reDrawMaze() {
/*Button Handle for 'New Maze' */
var startCol = Math.floor(Math.random() * 10) - 1;
var startRow = Math.floor(Math.random() * 10) - 1;
clearCanvas();
drawBase();
}
function generateMaze(row, col) {
/* Depth First Search*/
var currentTile = tiles[row][col];
var neighbor = findNeighbor(row, col);
/*Check if cell has been visited */
if (!currentTile.visited) {
currentTile.visited = true;
visitedStk.push(currentTile);
}
/* Break Case */
if (visitedStk.length == 0) {
redrawTiles();
return;
}
/*If a neighbor is found*/
else if (neighbor !== undefined) {
/*Break the wall in between*/
if (neighbor.row > currentTile.row) { /*Bottom*/
currentTile.bottom = false;
neighbor.top = false;
}
if (neighbor.row < currentTile.row) { /*Top*/
currentTile.top = false;
neighbor.bottom = false;
}
if (neighbor.col < currentTile.col) { /*Left*/
currentTile.left = false;
neighbor.right = false;
}
if (neighbor.col > currentTile.col) { /*Right*/
currentTile.right = false;
neighbor.left = false;
}
/*Update Current Tile*/
currentTile = neighbor;
}
/*If no neighbor was found, backtrack to a previous cell on the stacke*/
else {
var backtrack = visitedStk.pop();
generateMaze(backtrack.row, backtrack.col);
currentTile = backtrack;
}
generateMaze(currentTile.row, currentTile.col);
}
function findNeighbor(row, col) {
/*Find the neighbor of the given tile using the tiles array.*/
var top, bottom, left, right;
var stk = []
var neighbor = undefined;
var n;
/* Check for left neighbor */
if (row >= 0 && col > 0) {
left = tiles[row][col - 1];
(!left.visited) ? stk.push(left): undefined
}
/* Check for right neighbor */
if (row >= 0 && col < 9) {
right = tiles[row][col + 1];
(!right.visited) ? stk.push(right): undefined;
}
/* Check for top neighbor */
if (col >= 0 && row > 0) {
top = tiles[row - 1][col];
(!top.visited) ? stk.push(top): undefined
}
/* Check for bottom neighbor */
if (col >= 0 && row < 9) {
bottom = tiles[row + 1][col];
(!bottom.visited) ? stk.push(bottom): undefined
}
var len;
while (stk.length > 0) {
/* Choose a random neighbor */
len = stk.length;
n = Math.floor(Math.random() * stk.length);
neighbor = stk[n];
if (!neighbor.visited) {
break;
} else {
stk.splice(n, 1);
}
}
/*Return, will return undefined if no neighbor is found*/
return neighbor;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.2/jquery.min.js"></script>
<div id="maze" style="width:500px; margin:0 auto;">
<canvas id="mazeCanvas" width="550" height="550"></canvas>
</div>
<div id="buttons">
<hr />
<button id="newMazeBtn">New Maze</button>
<button id="aboutBtn">About</button>
</div>
The gray lines shouldn't be there and I don't know why they are.

It's good to see others tackling maze generation! It's a lot of fun. :)
It looks like you're getting tripped up by swapping the row/column when you're drawing the maze. If you look in your redrawTiles function, you'll see that you're treating i as the row, and j as the column (because you're accessing the current tile as tiles[i][j], and drawBase sets up the array in row-major order).
However, drawCell expects the first parameter to be x (the column), rather than y (the row), but you're passing i (the row) as the first parameter. Thus, when you call drawCell, the row is being interpreted as the x-coordinate, and the column as the y-coordinate, rather than the other way around.
Swapping those first two arguments to drawCell fixes the issue. I would strongly recommend using variables named row and column, instead of i and j, and I'd also recommend standardizing all your functions so that if they declare row/column parameters, the row comes first, and then the column. That way you'll be less likely to trip over this issue.
Hope that helps!

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JS Canvas movement animation loop

I have an object rendered to a canvas. I'm trying to get the object to move along a set path on a loop. Here is what I have:
// Canvas Element
var canvas = null;
// Canvas Draw
var ctx = null;
// Static Globals
var tileSize = 16,
mapW = 10,
mapH = 10;
// Instances of entities
var entities = [
// A single entity that starts at tile 28, and uses the setPath() function
{
id: 0,
tile: 28,
xy: tileToCoords(28),
width: 16,
height: 24,
speedX: 0,
speedY: 0,
logic: {
func: 'setPath',
// These are the parameters that go into the setPath() function
data: [0, ['down', 'up', 'left', 'right'], tileToCoords(28), 0]
},
dir: {up:false, down:false, left:false, right:false}
}
];
// Array for tile data
var map = [];
window.onload = function(){
// Populate the map array with a blank map and 4 walls
testMap();
canvas = document.getElementById('save');
ctx = canvas.getContext("2d");
// Add all the entities to the map array and start their behavior
for(var i = 0; i < entities.length; ++i){
map[entities[i].tile].render.object = entities[i].id;
if(entities[i].logic){
window[entities[i].logic.func].apply(null, entities[i].logic.data);
}
}
drawGame(map);
window.requestAnimationFrame(function(){
mainLoop();
});
};
function drawGame(map){
ctx.clearRect(0, 0, canvas.width, canvas.height);
// We save all the entity data for later so the background colors don't get rendered on top
var tileObjData = [];
for(var y = 0; y < mapH; ++y){
for(var x = 0; x < mapW; ++x){
var currentPos = ((y*mapW)+x);
ctx.fillStyle = map[currentPos].render.base;
ctx.fillRect(x*tileSize, y*tileSize, tileSize, tileSize);
var thisObj = map[currentPos].render.object;
if(thisObj !== false){
thisObj = entities[thisObj];
var originX = thisObj.xy.x;
var originY = thisObj.xy.y;
tileObjData.push(
{
id: thisObj.id,
originX: originX,
originY: originY,
width: thisObj.width,
height: thisObj.height,
}
);
}
}
}
// Draw all the entities after the background tiles are drawn
for(var i = 0; i < tileObjData.length; ++i){
drawEntity(tileObjData[i].id, tileObjData[i].originX, tileObjData[i].originY, tileObjData[i].width, tileObjData[i].height);
}
}
// Draws the entity data
function drawEntity(id, posX, posY, sizeX, sizeY){
var offX = posX + entities[id].speedX;
var offY = posY + entities[id].speedY;
ctx.fillStyle = '#00F';
ctx.fillRect(offX, offY + sizeX - sizeY, sizeX, sizeY);
entities[id].xy.x = offX;
entities[id].xy.y = offY;
}
// Redraws the canvas with the browser framerate
function mainLoop(){
drawGame(map);
for(var i = 0; i < entities.length; ++i){
animateMove(i, entities[i].dir.up, entities[i].dir.down, entities[i].dir.left, entities[i].dir.right);
}
window.requestAnimationFrame(function(){
mainLoop();
});
}
// Sets the speed, direction, and collision detection of an entity
function animateMove(id, up, down, left, right){
var prevTile = entities[id].tile;
if(up){
var topLeft = {x: entities[id].xy.x, y: entities[id].xy.y};
var topRight = {x: entities[id].xy.x + entities[id].width - 1, y: entities[id].xy.y};
if(!map[coordsToTile(topLeft.x, topLeft.y - 1)].state.passable || !map[coordsToTile(topRight.x, topRight.y - 1)].state.passable){
entities[id].speedY = 0;
}
else{
entities[id].speedY = -1;
}
}
else if(down){
var bottomLeft = {x: entities[id].xy.x, y: entities[id].xy.y + entities[id].width - 1};
var bottomRight = {x: entities[id].xy.x + entities[id].width - 1, y: entities[id].xy.y + entities[id].width - 1};
if(!map[coordsToTile(bottomLeft.x, bottomLeft.y + 1)].state.passable || !map[coordsToTile(bottomRight.x, bottomRight.y + 1)].state.passable){
entities[id].speedY = 0;
}
else{
entities[id].speedY = 1;
}
}
else{
entities[id].speedY = 0;
}
if(left){
var bottomLeft = {x: entities[id].xy.x, y: entities[id].xy.y + entities[id].width - 1};
var topLeft = {x: entities[id].xy.x, y: entities[id].xy.y};
if(!map[coordsToTile(bottomLeft.x - 1, bottomLeft.y)].state.passable || !map[coordsToTile(topLeft.x - 1, topLeft.y)].state.passable){
entities[id].speedX = 0;
}
else{
entities[id].speedX = -1;
}
}
else if(right){
var bottomRight = {x: entities[id].xy.x + entities[id].width - 1, y: entities[id].xy.y + entities[id].width - 1};
var topRight = {x: entities[id].xy.x + entities[id].width - 1, y: entities[id].xy.y};
if(!map[coordsToTile(bottomRight.x + 1, bottomRight.y)].state.passable || !map[coordsToTile(topRight.x + 1, topRight.y)].state.passable){
entities[id].speedX = 0;
}
else{
entities[id].speedX = 1;
}
}
else{
entities[id].speedX = 0;
}
entities[id].tile = coordsToTile(entities[id].xy.x + (entities[id].width / 2), entities[id].xy.y + (tileSize / 2));
map[entities[id].tile].render.object = id;
if(prevTile !== entities[id].tile){
map[prevTile].render.object = false;
}
}
//////////////////////////////////////
// THIS IS WHERE I'M HAVING TROUBLE //
//////////////////////////////////////
// A function that can be used by an entity to move along a set path
// id = The id of the entity using this function
// path = An array of strings that determine the direction of movement for a single tile
// originPoint = Coordinates of the previous tile this entity was at. This variable seems to be where problems happen with this logic. It should get reset for every tile length moved, but it only gets reset once currently.
// step = The current index of the path array
function setPath(id, path, originPoint, step){
// Determine if the entity has travelled one tile from the origin
var destX = Math.abs(entities[id].xy.x - originPoint.x);
var destY = Math.abs(entities[id].xy.y - originPoint.y);
if(destX >= tileSize || destY >= tileSize){
// Go to the next step in the path array
step = step + 1;
if(step >= path.length){
step = 0;
}
// Reset the origin to the current tile coordinates
originPoint = entities[id].xy;
}
// Set the direction based on the current index of the path array
switch(path[step]) {
case 'up':
entities[id].dir.up = true;
entities[id].dir.down = false;
entities[id].dir.left = false;
entities[id].dir.right = false;
break;
case 'down':
entities[id].dir.up = false;
entities[id].dir.down = true;
entities[id].dir.left = false;
entities[id].dir.right = false;
break;
case 'left':
entities[id].dir.up = false;
entities[id].dir.down = false;
entities[id].dir.left = true;
entities[id].dir.right = false;
break;
case 'right':
entities[id].dir.up = false;
entities[id].dir.down = false;
entities[id].dir.left = false;
entities[id].dir.right = true;
break;
};
window.requestAnimationFrame(function(){
setPath(id, path, originPoint, step);
});
}
// Take a tile index and return x,y coordinates
function tileToCoords(tile){
var yIndex = Math.floor(tile / mapW);
var xIndex = tile - (yIndex * mapW);
var y = yIndex * tileSize;
var x = xIndex * tileSize;
return {x:x, y:y};
}
// Take x,y coordinates and return a tile index
function coordsToTile(x, y){
var tile = ((Math.floor(y / tileSize)) * mapW) + (Math.floor(x / tileSize));
return tile;
}
// Generate a map array with a blank map and 4 walls
function testMap(){
for(var i = 0; i < (mapH * mapW); ++i){
// Edges
if (
// top
i < mapW ||
// left
(i % mapW) == 0 ||
// right
((i + 1) % mapW) == 0 ||
// bottom
i > ((mapW * mapH) - mapW)
) {
map.push(
{
id: i,
render: {
base: '#D35',
object: false,
sprite: false
},
state: {
passable: false
}
},
);
}
else{
// Grass
map.push(
{
id: i,
render: {
base: '#0C3',
object: false,
sprite: false
},
state: {
passable: true
}
},
);
}
}
}
<!DOCTYPE html>
<html>
<head>
<style>
body{
background-color: #000;
display: flex;
align-items: center;
justify-content: center;
color: #FFF;
font-size: 18px;
padding: 0;
margin: 0;
}
main{
width: 100%;
max-width: 800px;
margin: 10px auto;
display: flex;
align-items: flex-start;
justify-content: center;
flex-wrap: wrap;
}
.game{
width: 1000px;
height: 1000px;
position: relative;
}
canvas{
image-rendering: -moz-crisp-edges;
image-rendering: -webkit-crisp-edges;
image-rendering: pixelated;
image-rendering: crisp-edges;
}
.game canvas{
position: absolute;
top: 0;
left: 0;
width: 800px;
height: 800px;
}
</style>
</head>
<body>
<main>
<div class="game">
<canvas id="save" width="200" height="200" style="z-index: 1;"></canvas>
</div>
</main>
</body>
</html>
The problem is with the setPath() function, and more specifically I think it's something with the originPoint variable. The idea is that setPath() moves the object one tile per path string, and originPoint should be the coordinates of the last tile visited (so it should only get updated once the object coordinates are one tile length away from the originPoint). Right now it only gets updated the first time and then stops. Hopefully someone can point out what I got wrong here.

Your condition to change the path direction I change it to have conditions for each direction, something like:
if ((entities[id].dir.left && entities[id].xy.x <= tileSize) ||
(entities[id].dir.right && entities[id].xy.x >= tileSize*8) ||
(entities[id].dir.up && entities[id].xy.y <= tileSize) ||
(entities[id].dir.down && entities[id].xy.y >= tileSize*8)) {
and the originPoint was just a reference you should do:
originPoint = JSON.parse(JSON.stringify(entities[id].xy));
See the working code below
// Canvas Element
var canvas = null;
// Canvas Draw
var ctx = null;
// Static Globals
var tileSize = 16,
mapW = 10,
mapH = 10;
// Instances of entities
var entities = [
// A single entity that starts at tile 28, and uses the setPath() function
{
id: 0,
tile: 28,
xy: tileToCoords(28),
width: 16,
height: 24,
speedX: 0,
speedY: 0,
logic: {
func: 'setPath',
// These are the parameters that go into the setPath() function
data: [0, ['down', 'left', 'down', 'left', 'up', 'left', 'left', 'right', 'up', 'right', 'down','right', "up"], tileToCoords(28), 0]
},
dir: {up:false, down:false, left:false, right:false}
}
];
// Array for tile data
var map = [];
window.onload = function(){
// Populate the map array with a blank map and 4 walls
testMap();
canvas = document.getElementById('save');
ctx = canvas.getContext("2d");
// Add all the entities to the map array and start their behavior
for(var i = 0; i < entities.length; ++i){
map[entities[i].tile].render.object = entities[i].id;
if(entities[i].logic){
window[entities[i].logic.func].apply(null, entities[i].logic.data);
}
}
drawGame(map);
window.requestAnimationFrame(function(){
mainLoop();
});
};
function drawGame(map){
ctx.clearRect(0, 0, canvas.width, canvas.height);
// We save all the entity data for later so the background colors don't get rendered on top
var tileObjData = [];
for(var y = 0; y < mapH; ++y){
for(var x = 0; x < mapW; ++x){
var currentPos = ((y*mapW)+x);
ctx.fillStyle = map[currentPos].render.base;
ctx.fillRect(x*tileSize, y*tileSize, tileSize, tileSize);
var thisObj = map[currentPos].render.object;
if(thisObj !== false){
thisObj = entities[thisObj];
var originX = thisObj.xy.x;
var originY = thisObj.xy.y;
tileObjData.push(
{
id: thisObj.id,
originX: originX,
originY: originY,
width: thisObj.width,
height: thisObj.height,
}
);
}
}
}
// Draw all the entities after the background tiles are drawn
for(var i = 0; i < tileObjData.length; ++i){
drawEntity(tileObjData[i].id, tileObjData[i].originX, tileObjData[i].originY, tileObjData[i].width, tileObjData[i].height);
}
}
// Draws the entity data
function drawEntity(id, posX, posY, sizeX, sizeY){
var offX = posX + entities[id].speedX;
var offY = posY + entities[id].speedY;
ctx.fillStyle = '#00F';
ctx.fillRect(offX, offY + sizeX - sizeY, sizeX, sizeY);
entities[id].xy.x = offX;
entities[id].xy.y = offY;
}
// Redraws the canvas with the browser framerate
function mainLoop(){
drawGame(map);
for(var i = 0; i < entities.length; ++i){
animateMove(i, entities[i].dir.up, entities[i].dir.down, entities[i].dir.left, entities[i].dir.right);
}
window.requestAnimationFrame(function(){
mainLoop();
});
}
// Sets the speed, direction, and collision detection of an entity
function animateMove(id, up, down, left, right){
var prevTile = entities[id].tile;
if(up){
var topLeft = {x: entities[id].xy.x, y: entities[id].xy.y};
var topRight = {x: entities[id].xy.x + entities[id].width - 1, y: entities[id].xy.y};
if(!map[coordsToTile(topLeft.x, topLeft.y - 1)].state.passable || !map[coordsToTile(topRight.x, topRight.y - 1)].state.passable){
entities[id].speedY = 0;
}
else{
entities[id].speedY = -1;
}
}
else if(down){
var bottomLeft = {x: entities[id].xy.x, y: entities[id].xy.y + entities[id].width - 1};
var bottomRight = {x: entities[id].xy.x + entities[id].width - 1, y: entities[id].xy.y + entities[id].width - 1};
if(!map[coordsToTile(bottomLeft.x, bottomLeft.y + 1)].state.passable || !map[coordsToTile(bottomRight.x, bottomRight.y + 1)].state.passable){
entities[id].speedY = 0;
}
else{
entities[id].speedY = 1;
}
}
else{
entities[id].speedY = 0;
}
if(left){
var bottomLeft = {x: entities[id].xy.x, y: entities[id].xy.y + entities[id].width - 1};
var topLeft = {x: entities[id].xy.x, y: entities[id].xy.y};
if(!map[coordsToTile(bottomLeft.x - 1, bottomLeft.y)].state.passable || !map[coordsToTile(topLeft.x - 1, topLeft.y)].state.passable){
entities[id].speedX = 0;
}
else{
entities[id].speedX = -1;
}
}
else if(right){
var bottomRight = {x: entities[id].xy.x + entities[id].width - 1, y: entities[id].xy.y + entities[id].width - 1};
var topRight = {x: entities[id].xy.x + entities[id].width - 1, y: entities[id].xy.y};
if(!map[coordsToTile(bottomRight.x + 1, bottomRight.y)].state.passable || !map[coordsToTile(topRight.x + 1, topRight.y)].state.passable){
entities[id].speedX = 0;
}
else{
entities[id].speedX = 1;
}
}
else{
entities[id].speedX = 0;
}
entities[id].tile = coordsToTile(entities[id].xy.x + (entities[id].width / 2), entities[id].xy.y + (tileSize / 2));
map[entities[id].tile].render.object = id;
if(prevTile !== entities[id].tile){
map[prevTile].render.object = false;
}
}
//////////////////////////////////////
// THIS IS WHERE I'M HAVING TROUBLE //
//////////////////////////////////////
// A function that can be used by an entity to move along a set path
// id = The id of the entity using this function
// path = An array of strings that determine the direction of movement for a single tile
// originPoint = Coordinates of the previous tile this entity was at. This variable seems to be where problems happen with this logic. It should get reset for every tile length moved, but it only gets reset once currently.
// step = The current index of the path array
function setPath(id, path, originPoint, step){
if ((entities[id].dir.left && entities[id].xy.x <= originPoint.x - tileSize) ||
(entities[id].dir.right && entities[id].xy.x >= originPoint.x + tileSize) ||
(entities[id].dir.up && entities[id].xy.y <= originPoint.y - tileSize) ||
(entities[id].dir.down && entities[id].xy.y >= originPoint.y + tileSize)) {
// Go to the next step in the path array
step = step + 1;
if(step >= path.length){
step = 0;
}
// Reset the origin to the current tile coordinates
originPoint = JSON.parse(JSON.stringify(entities[id].xy));
}
// Set the direction based on the current index of the path array
switch(path[step]) {
case 'up':
entities[id].dir.up = true;
entities[id].dir.down = false;
entities[id].dir.left = false
entities[id].dir.right = false;
break;
case 'down':
entities[id].dir.up = false;
entities[id].dir.down = true;
entities[id].dir.left = false;
entities[id].dir.right = false;
break;
case 'left':
entities[id].dir.up = false;
entities[id].dir.down = false;
entities[id].dir.left = true;
entities[id].dir.right = false;
break;
case 'right':
entities[id].dir.up = false;
entities[id].dir.down = false;
entities[id].dir.left = false;
entities[id].dir.right = true;
break;
};
window.requestAnimationFrame(function(){
setPath(id, path, originPoint, step);
});
}
// Take a tile index and return x,y coordinates
function tileToCoords(tile){
var yIndex = Math.floor(tile / mapW);
var xIndex = tile - (yIndex * mapW);
var y = yIndex * tileSize;
var x = xIndex * tileSize;
return {x:x, y:y};
}
// Take x,y coordinates and return a tile index
function coordsToTile(x, y){
var tile = ((Math.floor(y / tileSize)) * mapW) + (Math.floor(x / tileSize));
return tile;
}
// Generate a map array with a blank map and 4 walls
function testMap(){
for(var i = 0; i < (mapH * mapW); ++i){
// Edges
if (
// top
i < mapW ||
// left
(i % mapW) == 0 ||
// right
((i + 1) % mapW) == 0 ||
// bottom
i > ((mapW * mapH) - mapW)
) {
map.push(
{
id: i,
render: {
base: '#D35',
object: false,
sprite: false
},
state: {
passable: false
}
},
);
}
else{
// Grass
map.push(
{
id: i,
render: {
base: '#0C3',
object: false,
sprite: false
},
state: {
passable: true
}
},
);
}
}
}
<!DOCTYPE html>
<html>
<head>
<style>
body{
background-color: #000;
display: flex;
align-items: center;
justify-content: center;
color: #FFF;
font-size: 18px;
padding: 0;
margin: 0;
}
main{
width: 100%;
max-width: 800px;
margin: 10px auto;
display: flex;
align-items: flex-start;
justify-content: center;
flex-wrap: wrap;
}
.game{
width: 1000px;
height: 1000px;
position: relative;
}
canvas{
image-rendering: -moz-crisp-edges;
image-rendering: -webkit-crisp-edges;
image-rendering: pixelated;
image-rendering: crisp-edges;
}
.game canvas{
position: absolute;
top: 0;
left: 0;
width: 800px;
height: 800px;
}
</style>
</head>
<body>
<main>
<div class="game">
<canvas id="save" width="200" height="200" style="z-index: 1;"></canvas>
</div>
</main>
</body>
</html>

As someone has already solved your bug...
This is more than a solution to your problem as the real problem you are facing is complexity, long complex if statements using data structures representing the same information in different ways making it difficult to see simple errors in logic.
On top of that you have some poor style habits that compound the problem.
A quick fix will just mean you will be facing the next problem sooner. You need to write in a ways that reduces the chances of logic errors due to increasing complexity
Style
First style. Good style is very important
Don't assign null to declared variables. JavaScript should not need to use null, the exception to the rule is that some C++ coders infected the DOM API with null returns because they did not understand JavaScipt (or was a cruel joke), and now we are stuck with null
window is the default this (global this) and is seldom needed. Eg window.requestAnimationFrame is identical to just requestAnimationFrame and window.onload is identical to onload
Don't pollute your code with inaccurate, redundant and/or obvious comments, use good naming to provide the needed information. eg:
var map[]; has the comment // array of tile data Well really its an array that has data, who would have guessed, so the comment can be // tiles but then map is a rather ambiguous name. Remove the comment and give the variable a better name.
The comment // Static Globals above some vars. Javascript does not have static as a type so the comment is wrong and the "global's" part is "duh..."
Use const to declare constants, move all the magic numbers to the top and define them as named const. A name has meaning, an number in some code has next to no meaning.
Don't assign listener to the event name, it is unreliable and can be hijacked or overwritten. Always use addEventListener to assign an event listener
Be very careful with your naming. eg the function named coordsToTile is confusing as it does not return a tile, it returns a tile index, either change the function name to match the functions behavior, or change the behavior to match the name.
Don't use redundant intermediate functions, examples:
Your frame request requestAnimationFrame(function(){mainLoop()}); should skip the middle man and be requestAnimationFrame(mainLoop);
You use Function.apply to call the function window[entities[i].logic.func].apply(null, entities[i].logic.data);. apply is used to bind context this to the call, you don't use this in the function so you don't need use the apply. eg window[entities[i].logic.func](...entities[i].logic.data);
BTW being forced to use bracket notation to access a global is a sign of poor data structure. You should never do that.
JavaScript has an unofficial idiomatic styles, you should try to write JS in this style. Some examples from your code
else on the same line as closing }
Space after if, else, for, function() and befor else, opening block {
An id and an index are not the same, use idx or index for an index and id for an identifier
Keep it simple
The more complex you make your data structures the harder it is for you to maintain them.
Structured
Define objects to encapsulate and organize your data.
A global config object, that is transprotable ie can converted be to and from JSON. it contains all the magic numbers, defaults, type descriptions, and what not needed in the game.
Create a set of global utilities that do common repeated tasks, ie create coordinates, list of directions.
Define object that encapsulate the settings and behaviors specific only to that object.
Use polymorphic object design, meaning that different objects use named common behaviors and properties. In the example all drawable object have a function called draw that takes an argument ctx, all objects that can be updated have a function called update
Example
This example is a complete rewrite of your code and fixing your problem. It may be a little advanced, but it is only an example to look though an pick up some tips.
A quick description of the objects used.
Objects
config is transportable config data
testMap is an example map description
tileMap does map related stuff
Path Object encapsulating path logic
Entity Object a single moving entity
Tile Object representing a single tile
game The game state manager
Games have states, eg loading, intro, inPlay, gameOver etc. If you do not plan ahead and create a robust state manager you will find it very difficult to move from one state to the next
I have included the core of a finite state manager. The state manager is responsible for updating and rendering. it is also responsible for all state changes.
setTimeout(() => game.state = "setup", 0); // Will start the game
const canvas = document.getElementById('save');
const ctx = canvas.getContext("2d");
const point = (x = 0, y = 0) => ({x,y});
const dirs = Object.assign(
[point(0, -1), point(1), point(0,1), point(-1)], { // up, right, down, left
"u": 0, // defines index for direction string characters
"r": 1,
"d": 2,
"l": 3,
strToDirIdxs(str) { return str.toLowerCase().split("").map(char => dirs[char]) },
}
);
const config = {
pathIdx: 28,
pathTypes: {
standard: "dulr",
complex: "dulrldudlruldrdlrurdlurd",
},
tile: {size: 16},
defaultTileName: "grass",
entityTypes: {
e: {
speed: 1 / 32, // in fractions of a tile per frame
color: "#00F",
size: {x:16, y:24},
pathName: "standard",
},
f: {
speed: 1 / 16, // in fractions of a tile per frame
color: "#08F",
size: {x:18, y:18},
pathName: "complex",
},
},
tileTypes: {
grass: {
style: {baseColor: "#0C3", object: false, sprite: false},
state: {passable: true}
},
wall: {
style: {baseColor: "#D35", object: false, sprite: false},
state: {passable: false}
},
},
}
const testMap = {
displayChars: {
" " : "grass", // what characters mean
"#" : "wall",
"E" : "grass", // also entity spawn
"F" : "grass", // also entity spawn
},
special: { // spawn enties and what not
"E"(idx) { entities.push(new Entity(config.entityTypes.e, idx)) },
"F"(idx) { entities.push(new Entity(config.entityTypes.f, idx)) }
},
map: // I double the width and ignor every second characters as text editors tend to make chars thinner than high
// 0_1_2_3_4_5_6_7_8_9_ x coord
"####################\n" +
"##FF ## ##\n" +
"## ## ##\n" +
"## #### ##\n" +
"## ##\n" +
"## #### ##\n" +
"## ##\n" +
"## ##\n" +
"## EE##\n" +
"####################",
// 0_1_2_3_4_5_6_7_8_9_ x coord
}
const entities = Object.assign([],{
update() {
for (const entity of entities) { entity.update() }
},
draw(ctx) {
for (const entity of entities) { entity.draw(ctx) }
},
});
const tileMap = {
map: [],
mapToIndex(x, y) { return x + y * tileMap.width },
pxToIndex(x, y) { return x / config.tile.size | 0 + (y / config.tile.size | 0) * tileMap.width },
tileByIdx(idx) { return tileMap.map[idx] },
tileByIdxDir(idx, dir) { return tileMap.map[idx + dir.x + dir.y * tileMap.width] },
idxByDir(dir) { return dir.x + dir.y * tileMap.width },
create(mapConfig) {
tileMap.length = 0;
const rows = mapConfig.map.split("\n");
tileMap.width = rows[0].length / 2 | 0;
tileMap.height = rows.length;
canvas.width = tileMap.width * config.tile.size;
canvas.height = tileMap.height * config.tile.size;
var x, y = 0;
while (y < tileMap.height) {
const row = rows[y];
for (x = 0; x < tileMap.width; x += 1) {
const char = row[x * 2];
tileMap.map.push(new Tile(mapConfig.displayChars[char], x, y));
if (mapConfig.special[char]) {
mapConfig.special[char](tileMap.mapToIndex(x, y));
}
}
y++;
}
},
update () {}, // stub
draw(ctx) {
for (const tile of tileMap.map) { tile.draw(ctx) }
},
};
function Tile(typeName, x, y) {
typeName = config.tileTypes[typeName] ? typeName : config.defaultTileName;
const t = config.tileTypes[typeName];
this.idx = x + y * tileMap.width;
this.coord = point(x * config.tile.size, y * config.tile.size);
this.style = {...t.style};
this.state = {...t.state};
}
Tile.prototype = {
draw(ctx) {
ctx.fillStyle = this.style.baseColor;
ctx.fillRect(this.coord.x, this.coord.y, config.tile.size, config.tile.size);
}
};
function Path(pathName) {
if (typeof config.pathTypes[pathName] === "string") {
config.pathTypes[pathName] = dirs.strToDirIdxs(config.pathTypes[pathName]);
}
this.indexes = config.pathTypes[pathName];
this.current = -1;
}
Path.prototype = {
nextDir(tileIdx) {
var len = this.indexes.length;
while (len--) { // make sure we dont loop forever
const dirIdx = this.indexes[this.current];
if (dirIdx > - 1) {
const canMove = tileMap.tileByIdxDir(tileIdx, dirs[dirIdx]).state.passable;
if (canMove) { return dirs[dirIdx] }
}
this.current = (this.current + 1) % this.indexes.length;
}
}
};
function Entity(type, tileIdx) {
this.coord = point();
this.move = point();
this.color = type.color;
this.speed = type.speed;
this.size = {...type.size};
this.path = new Path(type.pathName);
this.pos = this.nextTileIdx = tileIdx;
this.traveled = 1; // unit dist between tiles 1 forces update to find next direction
}
Entity.prototype = {
set dir(dir) {
if (dir === undefined) { // dont move
this.move.y = this.move.x = 0;
this.nextTileIdx = this.tileIdx;
} else {
this.move.x = dir.x * config.tile.size;
this.move.y = dir.y * config.tile.size;
this.nextTileIdx = this.tileIdx + tileMap.idxByDir(dir);
}
},
set pos(tileIdx) {
this.tileIdx = tileIdx;
const tile = tileMap.map[tileIdx];
this.coord.x = tile.coord.x + config.tile.size / 2;
this.coord.y = tile.coord.y + config.tile.size / 2;
this.traveled = 0;
},
draw(ctx) {
const ox = this.move.x * this.traveled;
const oy = this.move.y * this.traveled;
ctx.fillStyle = this.color;
ctx.fillRect(ox + this.coord.x - this.size.x / 2, oy + this.coord.y - this.size.y / 2, this.size.x, this.size.y)
},
update(){
this.traveled += this.speed;
if (this.traveled >= 1) {
this.pos = this.nextTileIdx;
this.dir = this.path.nextDir(this.tileIdx);
}
}
};
const game = {
currentStateName: undefined,
currentState: undefined,
set state(str) {
if (game.states[str]) {
if (game.currentState && game.currentState.end) { game.currentState.end() }
game.currentStateName = str;
game.currentState = game.states[str];
if (game.currentState.start) { game.currentState.start() }
}
},
states: {
setup: {
start() {
tileMap.create(testMap);
game.state = "play";
},
end() {
requestAnimationFrame(game.render); // start the render loop
delete game.states.setup; // MAKE SURE THIS STATE never happens again
},
},
play: {
render(ctx) {
tileMap.update();
entities.update();
tileMap.draw(ctx);
entities.draw(ctx);
}
}
},
renderTo: ctx,
startTime: undefined,
time: 0,
render(time) {
if (game.startTime === undefined) { game.startTime = time }
game.time = time - game.startTime;
if (game.currentState && game.currentState.render) { game.currentState.render(game.renderTo) }
requestAnimationFrame(game.render);
}
};
body{
background-color: #000;
}
canvas{
image-rendering: pixelated;
position: absolute;
top: 0;
left: 0;
width: 400px;
height: 400px;
}
<canvas id="save" width="200" height="200" style="z-index: 1;"></canvas>
Please Note that there are some running states that have not been tested and as such may have a typo.
Also the tile map must be walled to contain entities or they will throw when they try to leave the playfield.
The code is designed to run in the snippet. To make it work in a standard page add above the very first line setTimeout(() => game.state = "setup", 0); the line addEventListener(load", () = { and after the very last line add the line });

Sprite vs Group Collider not working in phaser with enableBody set as true

I'm a bit new to JavaScript and have been playing around with Phaser lately. So I'm building an infinite side scroller and everything works fine except that my player won't collide with the walls. Both sprites have physics enabled and I have tried multiple solutions, none of which work. Can you please help me out?
function bloxo()
{
var game = new Phaser.Game(1200, 600, Phaser.CANVAS, 'gameStage', { preload: preload, create: create, update: update });
var prevHole = 3;
function preload() {
game.load.image('bloxoDown','../bloxo/assets/images/bloxoDown.png');
game.load.image('bloxoUp','../bloxo/assets/images/bloxoUp.png');
game.load.image('wall','../bloxo/assets/images/platform.png',400,200);
var space;
var esc;
var player;
var walls;
var score;
}
function create() {
//Canvas With a White Bacground and Physics is Created
game.stage.backgroundColor = "#ffffff";
game.physics.startSystem(Phaser.Physics.ARCADE);
//Sets the initial Score.
score = 0;
//Sets how fast the tiles move
tileSpeed = -300;
tileWidth = game.cache.getImage('wall').width;
tileHeight = game.cache.getImage('wall').height;;
//Keys for User Input are created
space = game.input.keyboard.addKey(Phaser.Keyboard.SPACEBAR);
esc = game.input.keyboard.addKey(Phaser.Keyboard.ESC);
//Adds Bloxo to the game as a sprite.
player = game.add.sprite(200,200,'bloxoDown');
player.scale.setTo(0.6, 0.6);
game.physics.enable(player, Phaser.Physics.ARCADE);
player.body.collideWorldBounds = true;
player.body.immovable = true;
//Walls Group is created
walls = game.add.physicsGroup();
walls.createMultiple(50, 'wall');
walls.enableBody = true;
game.physics.arcade.overlap(player, walls,null,this)
game.physics.arcade.collide(player,walls,gameOver);
// Stop the following keys from propagating up to the browser
game.input.keyboard.addKeyCapture([ Phaser.Keyboard.SPACEBAR, Phaser.Keyboard.ESC,]);
//Unpausing Function
window.onkeydown = function(event)
{
if (esc.onDown && (esc.timeDown > 2000))
{
if(game.paused)
{
game.paused = !game.paused;
pauseLbl.destroy();
}
}
}
//Add an initial platform
addWall();
//Add a platform every 3 seconds
var timerWorld = game.time.events.loop(500, addWall);
}
function update() {
if (space.isDown)
{
player.body.y -=5;
bloxoUp();
}
else
{
player.body.y +=5;
bloxoDown();
}
if(esc.isDown)
{
pauseGame();
}
}
function bloxoUp()
{
player.loadTexture('bloxoUp');
}
function bloxoDown()
{
player.loadTexture('bloxoDown');
}
function pauseGame()
{
game.paused = true;
pauseLbl = game.add.text(500, 300, 'Game Paused', { font: '30px Roboto', fill: '#aaaaaa' });
}
function addTile(x,y)
{
//Get a tile that is not currently on screen
var tile = walls.getFirstDead();
//Reset it to the specified coordinates
tile.reset(x,y);
tile.body.velocity.x = tileSpeed;
tile.body.immovable = true;
//When the tile leaves the screen, kill it
tile.checkWorldBounds = true;
tile.outOfBoundsKill = true;
}
function addWall()
{
//Speed up the game to make it harder
tileSpeed -= 1;
score += 1;
//Work out how many tiles we need to fit across the whole screen
var tilesNeeded = Math.ceil(game.world.height / tileHeight);
//Add a hole randomly somewhere
do
{
var hole = Math.floor(Math.random() * (tilesNeeded - 2)) + 1;
}while((hole > (prevHole + 2)) && (hole < (prevHole - 2)) );
prevHole = hole;
//Keep creating tiles next to each other until we have an entire row
//Don't add tiles where the random hole is
for (var i = 0; i < tilesNeeded; i++){
if (i != hole && (i != hole+1 && i != hole-1) && (i != hole+2 && i != hole-2)){
addTile(game.world.width, i * tileHeight);
}
}
}
function gameOver()
{
console.log("player hit");
player.kill();
game.state.start(game.state.current);
}
}

You have just to move collide call into your update method:
game.physics.arcade.collide(player, walls, gameOver);
Take a look to the runnable snippet below(I have resized the canvas for the preview, sorry) or Fiddle:
var game = new Phaser.Game(450, 150, Phaser.CANVAS, 'gameStage', {
preload: preload,
create: create,
update: update
});
var prevHole = 3;
function preload() {
game.load.image('bloxoDown', '../bloxo/assets/images/bloxoDown.png');
game.load.image('bloxoUp', '../bloxo/assets/images/bloxoUp.png');
game.load.image('wall', '../bloxo/assets/images/platform.png', 400, 100);
var space;
var esc;
var player;
var walls;
var score;
}
function create() {
//Canvas With a White Bacground and Physics is Created
game.stage.backgroundColor = "#ffffff";
game.physics.startSystem(Phaser.Physics.ARCADE);
//Sets the initial Score.
score = 0;
//Sets how fast the tiles move
tileSpeed = -300;
tileWidth = game.cache.getImage('wall').width;
tileHeight = game.cache.getImage('wall').height;;
//Keys for User Input are created
space = game.input.keyboard.addKey(Phaser.Keyboard.SPACEBAR);
esc = game.input.keyboard.addKey(Phaser.Keyboard.ESC);
//Adds Bloxo to the game as a sprite.
player = game.add.sprite(200, 200, 'bloxoDown');
player.scale.setTo(0.6, 0.6);
game.physics.enable(player, Phaser.Physics.ARCADE);
player.body.collideWorldBounds = true;
player.body.immovable = true;
//Walls Group is created
walls = game.add.physicsGroup();
walls.createMultiple(50, 'wall');
walls.enableBody = true;
game.physics.arcade.overlap(player, walls, null, this)
// remove your call to collide
// Stop the following keys from propagating up to the browser
game.input.keyboard.addKeyCapture([Phaser.Keyboard.SPACEBAR, Phaser.Keyboard.ESC, ]);
//Unpausing Function
window.onkeydown = function(event) {
if (esc.onDown && (esc.timeDown > 2000)) {
if (game.paused) {
game.paused = !game.paused;
pauseLbl.destroy();
}
}
}
//Add an initial platform
addWall();
//Add a platform every 3 seconds
var timerWorld = game.time.events.loop(500, addWall);
}
function update() {
if (space.isDown) {
player.body.y -= 5;
bloxoUp();
} else {
player.body.y += 5;
bloxoDown();
}
// move your collide call here
game.physics.arcade.collide(player, walls, gameOver);
if (esc.isDown) {
pauseGame();
}
}
function bloxoUp() {
player.loadTexture('bloxoUp');
}
function bloxoDown() {
player.loadTexture('bloxoDown');
}
function pauseGame() {
game.paused = true;
pauseLbl = game.add.text(500, 300, 'Game Paused', {
font: '30px Roboto',
fill: '#aaaaaa'
});
}
function addTile(x, y) {
//Get a tile that is not currently on screen
var tile = walls.getFirstDead();
//Reset it to the specified coordinates
if (tile) {
tile.reset(x, y);
tile.body.velocity.x = tileSpeed;
tile.body.immovable = true;
//When the tile leaves the screen, kill it
tile.checkWorldBounds = true;
tile.outOfBoundsKill = true;
}
}
function addWall() {
//Speed up the game to make it harder
tileSpeed -= 1;
score += 1;
//Work out how many tiles we need to fit across the whole screen
var tilesNeeded = Math.ceil(game.world.height / tileHeight);
var prevHole;
//Add a hole randomly somewhere
do {
var hole = Math.floor(Math.random() * (tilesNeeded - 2)) + 1;
} while ((hole > (prevHole + 2)) && (hole < (prevHole - 2)));
prevHole = hole;
//Keep creating tiles next to each other until we have an entire row
//Don't add tiles where the random hole is
for (var i = 0; i < tilesNeeded; i++) {
if (i != hole && (i != hole + 1 && i != hole - 1) && (i != hole + 2 && i != hole - 2)) {
addTile(game.world.width, i * tileHeight);
}
}
}
function gameOver() {
console.log("player hit");
player.kill();
game.state.start(game.state.current);
}
canvas{
border: 5px solid #333;
margin-left:25px;
margin-top:25px;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/phaser/2.6.2/phaser.min.js"></script>

Adobe Animate CC not drawing anything on publish/test. Java-issue? HTML5-canvast document

When I test or publish my project, which is a jigsaw puzzle from this tutorial: https://www.youtube.com/watch?v=uCQuUZs3UGE
Nothing gets drawn except the grey background. No puzzle pices nor any puzzle shape is drawn at all. I also get a warning:
WARNINGS:
Frame numbers in EaselJS start at 0 instead of 1. For example, this affects gotoAndStop and gotoAndPlay calls. (17)
But that should just be a warning, not an error. So might there be an error in my javascript code? This is the code, its fairly simple:
//************
// Initialize;
var numPieces = 16;
for (var i = 0; i = < numPieces; i++)
{
var pieceName = "p" + (i + 1);
var piece = this[pieceName];
if (piece)
{
piece.name = pieceName;
piece.on("mousedown", function(evt)
{
this.scaleX = 1;
this.scaleY = 1;
this.shadow = null;
this.parent.addChild(this);
this.offset = (x:this.x - evt.stageX, y:this.y - evt.stageY);
});
piece.on("pressmove", function (evt)
{
this.x = evt.stageX + this.offset.x;
this.y = evt.stageY + this.offset.y;
});
piece.on("pressup", function(evt)
{
var target = this.parent["t"+this.name.substr(1)];
if (target && hitTestInRange(target, 30) )
{
this.x = target.x;
this.y = target.y;
}
});
}
}
function hitTestInRange( target, range )
{
if (target.x > stage.mouseX - range &&
target.x < stage.mouseX + range &&
target.y > stage.mouseY - range &&
target.y < stage.mouseY + range)
{
return true;
}
return false;
}
I also included a screenshot of the project. screenshot
Thanks in advance

Draw clickable grid of 1 million squares

I need to find a way to draw a 1000x1000 squares grid, each square is clickable and they must be independently color changeable. Like mines game. I can use HTML (pure or using Canvas or SVG), CSS and JavaScript for this.
I know how to create one grid with these characteristics with JavaScript and CSS, it does well with 10x10 squares, with 100x100 the squares will turn into tall rectangles and 1000x1000 it loads, but the "squares" are soo much compressed that borders meet each other and renders a full gray page.
I tried using HTML and JavaScript to draw SVG squares, the squares' size problem solves, but I don't know how to make they change color when clicked and when I set to load 1000x1000 squares it will freeze the browse and eventually crash the tab.
Is this feasible in any way?
EDIT
Sorry if I wasn't clear, but yes, I need scroll bars in that. They are no problem for me.
You can see the two trials I described here:
JavaScript and CSS
var lastClicked;
var grid = clickableGrid(100,100,function(el,row,col,i){
console.log("You clicked on element:",el);
console.log("You clicked on row:",row);
console.log("You clicked on col:",col);
console.log("You clicked on item #:",i);
el.className='clicked';
if (lastClicked) lastClicked.className='';
lastClicked = el;
});
document.body.appendChild(grid);
function clickableGrid( rows, cols, callback ){
var i=0;
var grid = document.createElement('table');
grid.className = 'grid';
for (var r=0;r<rows;++r){
var tr = grid.appendChild(document.createElement('tr'));
for (var c=0;c<cols;++c){
var cell = tr.appendChild(document.createElement('td'));
++i;
cell.addEventListener('click',(function(el,r,c,i){
return function(){
callback(el,r,c,i);
}
})(cell,r,c,i),false);
}
}
return grid;
}
.grid { margin:1em auto; border-collapse:collapse }
.grid td {
cursor:pointer;
width:30px; height:30px;
border:1px solid #ccc;
}
.grid td.clicked {
background-color:gray;
}
JavaScript and HTML
document.createSvg = function(tagName) {
var svgNS = "http://www.w3.org/2000/svg";
return this.createElementNS(svgNS, tagName);
};
var numberPerSide = 20;
var size = 10;
var pixelsPerSide = 400;
var grid = function(numberPerSide, size, pixelsPerSide, colors) {
var svg = document.createSvg("svg");
svg.setAttribute("width", pixelsPerSide);
svg.setAttribute("height", pixelsPerSide);
svg.setAttribute("viewBox", [0, 0, numberPerSide * size, numberPerSide * size].join(" "));
for(var i = 0; i < numberPerSide; i++) {
for(var j = 0; j < numberPerSide; j++) {
var color1 = colors[(i+j) % colors.length];
var color2 = colors[(i+j+1) % colors.length];
var g = document.createSvg("g");
g.setAttribute("transform", ["translate(", i*size, ",", j*size, ")"].join(""));
var number = numberPerSide * i + j;
var box = document.createSvg("rect");
box.setAttribute("width", size);
box.setAttribute("height", size);
box.setAttribute("fill", color1);
box.setAttribute("id", "b" + number);
g.appendChild(box);
svg.appendChild(g);
}
}
svg.addEventListener(
"click",
function(e){
var id = e.target.id;
if(id)
alert(id.substring(1));
},
false);
return svg;
};
var container = document.getElementById("container");
container.appendChild(grid(100, 10, 2000, ["gray", "white"]));
<div id="container">
</div>
I will be trying implementing the given answers and ASAP I'll accept or update this question. Thanks.
SOLUTION
Just to record, I managed to do it using canvas to draw the grid and the clicked squares and added an event listener to know where the user clicks.
Here is the code in JavaScript and HTML:
function getSquare(canvas, evt) {
var rect = canvas.getBoundingClientRect();
return {
x: 1 + (evt.clientX - rect.left) - (evt.clientX - rect.left)%10,
y: 1 + (evt.clientY - rect.top) - (evt.clientY - rect.top)%10
};
}
function drawGrid(context) {
for (var x = 0.5; x < 10001; x += 10) {
context.moveTo(x, 0);
context.lineTo(x, 10000);
}
for (var y = 0.5; y < 10001; y += 10) {
context.moveTo(0, y);
context.lineTo(10000, y);
}
context.strokeStyle = "#ddd";
context.stroke();
}
function fillSquare(context, x, y){
context.fillStyle = "gray"
context.fillRect(x,y,9,9);
}
var canvas = document.getElementById('myCanvas');
var context = canvas.getContext('2d');
drawGrid(context);
canvas.addEventListener('click', function(evt) {
var mousePos = getSquare(canvas, evt);
fillSquare(context, mousePos.x, mousePos.y)
}, false);
<body>
<canvas id="myCanvas" width="10000" height="10000"></canvas>
</body>

Generating such a large grid with HTML is bound to be problematic.
Drawing the grid on a Canvas and using a mouse-picker technique to determine which cell was clicked would be much more efficient.
This would require 1 onclick and/or hover event instead of 1,000,000.
It also requires much less HTML code.

I wouldn't initialize all the squares right off, but instead as they are clicked -
(function() {
var divMain = document.getElementById('main'),
divMainPosition = divMain.getBoundingClientRect(),
squareSize = 4,
square = function(coord) {
var x = coord.clientX - divMainPosition.x + document.body.scrollLeft +
document.documentElement.scrollLeft,
y = coord.clientY - divMainPosition.y + document.body.scrollTop +
document.documentElement.scrollTop;
return {
x:Math.floor(x / squareSize),
y:Math.floor(y / squareSize)
}
}
divMain.addEventListener('click', function(evt) {
var sqr = document.createElement('div'),
coord = square(evt);
sqr.className = 'clickedSquare';
sqr.style.width = squareSize + 'px';
sqr.style.height = squareSize + 'px';
sqr.style.left = (coord.x * squareSize) + 'px';
sqr.style.top = (coord.y * squareSize) + 'px';
sqr.addEventListener('click', function(evt) {
console.log(this);
this.parentNode.removeChild(this);
evt.stopPropagation();
});
this.appendChild(sqr);
});
}());
#main {
width:4000px;
height:4000px;
background-color:#eeeeee;
position:relative;
}
.clickedSquare {
background-color:#dd8888;
position:absolute;
}
<div id="main">
</div>
Uses CSS positioning to determine which square was clicked on,
doesn't initialize a square until it's needed.
Granted I imagine this would start to have a negative impact to use r experience, but that would ultimately depend on their browser and machine.

Use the same format you noramlly use, but add this:
sqauareElement.height = 10 //height to use
squareElement.width = 10 //width to use
This will add quite a large scroll due to the size, but it's the only logical explanation I can come up with.

The canvas approach is fine, but event delegation makes it possible to do this with a table or <div> elements with a single listener:
const tbodyEl = document.querySelector("table tbody");
tbodyEl.addEventListener("click", event => {
const cell = event.target.closest("td");
if (!cell || !tbodyEl.contains(cell)) {
return;
}
const row = +cell.getAttribute("data-row");
const col = +cell.getAttribute("data-col");
console.log(row, col);
});
const rows = 100;
const cols = 100;
for (let i = 0; i < rows; i++) {
const rowEl = document.createElement("tr");
tbodyEl.appendChild(rowEl);
for (let j = 0; j < cols; j++) {
const cellEl = document.createElement("td");
rowEl.appendChild(cellEl);
cellEl.classList.add("cell");
cellEl.dataset.row = i;
cellEl.dataset.col = j;
}
}
.cell {
height: 4px;
width: 4px;
cursor: pointer;
border: 1px solid black;
}
table {
border-collapse: collapse;
}
<table><tbody></tbody></table>

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