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.png flickers while animating using drawImage in canvas javascript

I have created a simple game using Canvas in Javascript where the player has to avoid obstacles by jumping over or shrinking. The obstacle images, which are animated moving towards the left, flickers at some sort of interval. The interval increases in parallel with the gameSpeed variable, making me wonder if this might have something to do with either the spawnObstacle() or the update() functions. Another reason why I believe so is because neither the drawn playerImg.png nor the drawn Score/Highscore ever flickers. I have tried several different solutions found online, but none seem to solve my problem.
Here is my index.js and index.html below:
import {registerNewHighscore, makeList} from "./globalHs.js";
const canvas = document.getElementById('game');
const ctx = canvas.getContext('2d');
const newGameBtn = document.getElementById("newGame");
const seeInstrBtn = document.getElementById("instrBtn");
const seeHsBtn = document.getElementById("hsBtn");
const goBackBtn = document.getElementById("backBtn");
let score;
let highscore;
let scoreText;
let highscoreText;
let player;
let gravity;
let obstacles = [];
let gameSpeed;
let keyPressed;
let isKeyPressed = false
let active = true;
let rotation = 0;
ctx.canvas.width = window.innerWidth;
ctx.canvas.height = window.innerHeight;
function createImage(path){
let image = new Image();
image.src = path;
return image;
}
const obsImg = createImage("img/chatbubble.png");
const rockImg = createImage("img/rock.png");
const roadblockImg = createImage("img/roadblock.png");
const playerImg = createImage("img/logoPlayer.png");
newGameBtn.addEventListener('click', function() {
document.getElementById("newGame").style.display = "none";
document.getElementById("header").style.display = "none";
document.getElementById("instr").style.display = "none";
document.getElementById("main").style.display = "block";
document.getElementById("instrBtn").style.display = "none";
document.getElementById("hsBtn").style.display = "none";
document.getElementById("hsBoard").style.display = "none";
start();
});
seeInstrBtn.addEventListener('click', function(){
document.getElementById("header").style.display = "none";
document.getElementById("instrBtn").style.display = "none";
document.getElementById("newGame").style.display = "none";
document.getElementById("instr").style.display = "block";
document.getElementById("instr").style.visibility = "visible";
document.getElementById("backBtn").style.display = "block";
document.getElementById("hsBtn").style.display = "none";
document.getElementById("hsBoard").style.display = "none";
document.getElementById("backBtn").style.top = "50%";
});
seeHsBtn.addEventListener('click', function(){
document.getElementById("header").style.display = "none";
document.getElementById("hsBtn").style.display = "none";
document.getElementById("newGame").style.display = "none";
document.getElementById("instrBtn").style.display = "none";
document.getElementById("instr").style.display = "none";
document.getElementById("hsBoard").style.display = "block";
document.getElementById("backBtn").style.display = "block";
document.getElementById("backBtn").style.top = "70%";
makeList();
});
goBackBtn.addEventListener('click', function() {
goBack();
});
function goBack() {
document.getElementById("backBtn").style.display = "none";
document.getElementById("instr").style.display = "none";
document.getElementById("header").style.display = "block";
document.getElementById("newGame").style.display = "block";
document.getElementById("instrBtn").style.display = "block";
document.getElementById("hsBtn").style.display = "block";
document.getElementById("hsBoard").style.display = "none";
};
document.addEventListener('keydown', function(evt) {
if (isKeyPressed) return;
isKeyPressed = true;
keyPressed = evt.code;
});
document.addEventListener('keyup', function(evt) {
if (evt.code !== keyPressed) return; // only respond to the key already pressed
isKeyPressed = false;
keyPressed = null;
});
function randomIntInRange (min, max){
return Math.round(Math.random() * (max - min) + min);
}
class Player{
constructor (x, y, r, w, h, playerImg){
this.playerImg = playerImg;
this.x = x;
this.y = y;
this.r = r;
this.w = r*2;
this.h = r*2;
this.dy = 0;
this.jumpForce = 18;
this.originalRad = r;
this.grounded = false;
this.jumpTimer = 0;
/* this.newRotation = 0; */
}
animate () {
if (['Space', 'KeyW'].includes(keyPressed)) {
this.jump();
} else{
this.jumpTimer = 0;
}
if (['ShiftLeft', 'KeyS'].includes(keyPressed)){
/* this.newRotation = rotation * 2; */
this.r = this.originalRad / 2;
this.w = this.originalRad;
this.h = this.originalRad;
} else {
/* this.newRotation = rotation; */
this.r = this.originalRad;
this.w = this.r * 2;
this.h = this.r * 2;
}
this.y += this.dy;
if (this.y + this.r < canvas.height){
this.dy += gravity;
this.grounded = false;
} else{
this.dy = 0;
this.grounded = true;
this.y = canvas.height - this.r;
}
this.draw();
}
jump () {
if (this.r != this.originalRad) return;
if (this.grounded && this.jumpTimer == 0){
this.jumpTimer = 1.5;
this.dy = -this.jumpForce;
} else if (this.jumpTimer > 0 && this.jumpTimer < 15){
this.jumpTimer++;
this.dy = -this.jumpForce - (this.jumpTimer / 50);
}
}
draw () {
ctx.translate(this.x, this.y);
ctx.rotate(rotation);
ctx.translate(-(this.x), -(this.y));
ctx.drawImage(this.playerImg, (this.x-this.r), (this.y-this.r), this.w, this.h);
ctx.setTransform(1, 0, 0, 1, 0, 0);
}
}
class Obstacle {
constructor (x, y, w, h, obsImg){
this.obsImg = obsImg;
this.x = x,
this.y = y,
this.w = w;
this.h = h;
this.dx = -gameSpeed;
obsImg.width = this.w;
obsImg.height = this.h;
}
update (){
this.x += this.dx;
this.dx = -gameSpeed;
}
draw () {
ctx.beginPath();
ctx.fillStyle = "rgba(0, 0, 0, 0)";
ctx.fillRect(this.x, this.y, this.w, this.h,);
ctx.drawImage(this.obsImg, this.x, this.y, this.w*1.1, this.h);
ctx.closePath();
}
/////// CIRCLE
/*draw () {
ctx.beginPath();
ctx.arc(this.x, this.y, this.r, 0, (2 * Math.PI), false)
ctx.fillStyle = this.c;
ctx.fill();
ctx.closePath();
}*/
/////// ELLIPSE
/*draw () {
ctx.beginPath();
ctx.ellipse(this.x, this.y, this.radX, this.radY, 0, 0, 2 * Math.PI);
ctx.fillStyle = this.c;
ctx.fill();
ctx.stroke();
}*/
}
class Rock {
constructor (x, y, w, h, rockImg){
this.rockImg = rockImg;
this.x = x,
this.y = y,
this.w = w;
this.h = h;
this.dx = -gameSpeed;
rockImg.width = this.w;
rockImg.height = this.h;
}
update (){
this.x += this.dx;
this.dx = -gameSpeed;
}
draw () {
ctx.beginPath();
ctx.fillStyle = "rgba(0, 0, 0, 0)";
ctx.fillRect(this.x+20, this.y+40, this.w-20, this.h-40);
ctx.drawImage(this.rockImg, this.x-20, this.y, this.w*1.5, this.h*1.5);
ctx.closePath();
}
}
class Roadblock {
constructor (x, y, w, h, roadblockImg){
this.roadblockImg = roadblockImg;
this.x = x,
this.y = y,
this.w = w;
this.h = h;
this.dx = -gameSpeed;
roadblockImg.width = this.w;
roadblockImg.height = this.h;
}
update (){
this.x += this.dx;
this.dx = -gameSpeed;
}
draw () {
ctx.beginPath();
ctx.fillStyle = "rgba(0, 0, 0, 0)";
ctx.fillRect(this.x, this.y+15, this.w, this.h,);
ctx.drawImage(this.roadblockImg, this.x, this.y, this.w, this.h*1.15);
ctx.closePath();
}
}
class Text{
constructor(t, x, y, a, c, s){
this.t = t;
this.x = x;
this.y = y;
this.a = a;
this.c = c;
this.s = s;
}
draw () {
ctx.beginPath();
ctx.fillStyle = this.c;
ctx.font = this.s + "px";
ctx.textAlign = this.a;
ctx.fillText(this.t, this.x, this.y);
ctx.closePath();
}
}
function getDistance(player, obstacle) {
var distX = Math.abs(player.x - (obstacle.x + obstacle.w / 2));
var distY = Math.abs(player.y - (obstacle.y + obstacle.h / 2));
if (distX > (obstacle.w / 2 + player.r)) { return false; }
if (distY > (obstacle.h / 2 + player.r)) { return false; }
if (distX <= (obstacle.w)) { return true; }
if (distY <= (obstacle.h)) { return true; }
var dx = distX - obstacle.w / 2;
var dy = distY - obstacle.h / 2;
return (dx * dx + dy * dy <= (player.r*player.r));
}
let initialSpawnTimer = 200;
let spawnTimer = initialSpawnTimer;
function spawnObstacle (){
let sizeX;
let sizeY;
let type = randomIntInRange(0, 2);
let obstacle = new Obstacle(
canvas.width + sizeX,
canvas.height - sizeX,
sizeX,
sizeY,
obsImg
);
if (type == 0){
sizeX = randomIntInRange(100, 160);
sizeY = sizeX / 2;
obstacle = new Rock(
canvas.width + sizeX,
canvas.height - sizeY,
sizeX,
sizeY,
rockImg
);
} else if (type == 1){
sizeX = randomIntInRange(80, 160);
sizeY = sizeX / 2;
obstacle = new Obstacle(
canvas.width + sizeX,
canvas.height - sizeX,
sizeX,
sizeY,
obsImg
);
obstacle.y -= player.originalRad + randomIntInRange(-50, 150);
} else if (type == 2){
sizeX = 150;
sizeY = sizeX / 2;
obstacle = new Roadblock(
canvas.width + sizeX,
canvas.height - sizeY,
sizeX,
sizeY,
roadblockImg
);
}
obstacles.push(obstacle);
}
function start () {
ctx.canvas.width = window.innerWidth;
ctx.canvas.height = window.innerHeight;
ctx.font = "40px Courier New";
active = true;
gameSpeed = 6;
gravity = 1;
score = 0;
highscore = 0;
if (localStorage.getItem('highscore')){
highscore = localStorage.getItem('highscore');
}
player = new Player(100, 0, 50, 100, 100, playerImg);
scoreText = new Text("Score: " + score, 45, 45, "left", "#212121", "40");
highscoreText = new Text("Highscore: " + highscore, 45,
90, "left", "gold", "40");
window.requestAnimationFrame(update);
}
let lastTime;
function update (time) {
if (lastTime != null) {
const delta = time - lastTime;
}
ctx.clearRect(0, 0, canvas.width, canvas.height);
spawnTimer--;
if (spawnTimer <= 0){
spawnObstacle();
spawnTimer = initialSpawnTimer - gameSpeed * 8;
if (spawnTimer < 60){
spawnTimer = randomIntInRange(40, 80);
}
}
for (let i = 0; i < obstacles.length; i++){
let o = obstacles[i];
o.draw();
o.update();
if (o.x + o.y < 0){
obstacles.splice(i, 1);
}
if (getDistance(player, o)) {
active = false;
obstacles = [];
spawnTimer = initialSpawnTimer;
gameSpeed = 6;
window.localStorage.setItem('highscore', highscore);
score -= 1;
highscore -= 1;
if (score >= highscore){
registerNewHighscore(highscore+1);
}
goBack();
}
}
lastTime = time;
if (active){
window.requestAnimationFrame(update);
}
player.animate();
score++;
scoreText.t = "Score: " + score;
scoreText.draw();
if (score > highscore){
highscore = score;
highscoreText.t = "Highscore: " + highscore;
}
highscoreText.draw();
rotation+=Math.PI/180 * 2 + gameSpeed * 0.01;
gameSpeed += 0.002;
}
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
HTML:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Kindly Waiting Game V2</title>
<link rel="stylesheet" href="styles.css" />
</head>
<body>
<div class="world">
<div id="header">The Kindly Game</div>
<div id="newGame" onmouseover="this.style.backgroundColor = 'goldenrod'"
onmouseout="this.style.backgroundColor= 'gold'">New Game</div>
<div id="instrBtn" onmouseover="this.style.backgroundColor = 'goldenrod'" onmouseout="this.style.backgroundColor
= 'gold'">Instructions</div>
<div id="hsBtn" onmouseover="this.style.backgroundColor = 'goldenrod'" onmouseout="this.style.backgroundColor
= 'gold'">Highscores</div>
<div id="instr" style="display: none">Avoid the <br>chatbubbles, <br>roadblocks, <br>and rocks!<br><br>
Instructions: <br>Space/W: Jump <br>ShiftLeft/S: Shrink</div>
<div id="hsBoard" style="display: none">Highscores:</div>
<div id="backBtn" onmouseover="this.style.backgroundColor = 'goldenrod'" onmouseout="this.style.backgroundColor
= 'gold'">Back</div>
<div id="main"></div>
<div id="score"></div>
<div id="cloudLarge"></div>
<div id="cloudMedium"></div>
<div id="cloudSmall"></div>
<div id="cloudSmall2"></div>
<div id="ufo"></div>
<div id="airplane"></div>
<div id="ye"></div>
</div>
<canvas id="game" width="640" height="400"></canvas>
<script src="globalHs.js" type="module"></script>
<script src="index.js" type="module"></script>
</body>
</html>

Your issue is caused by this block of code inside your update() function:
if (o.x + o.y < 0){
obstacles.splice(i, 1);
}
Now while I don't know the exact logic why you're checking the sum of the obstacles' horizontal and vertical position, you're actually removing something from an array with the .splice() method. As this is happening inside a for-loop you're actually modifying the length of the array while it might still loop over it.
You can fix this by looping over the array from the last to the first element:
for (let i = obstacles.length-1; i>=0; i--) {
let o = obstacles[i];
o.draw();
o.update();
if (o.x + o.y < 0) {
obstacles.splice(i, 1);
}
if (getDistance(player, o)) {
active = false;
obstacles = [];
spawnTimer = initialSpawnTimer;
gameSpeed = 6;
window.localStorage.setItem('highscore', highscore);
score -= 1;
highscore -= 1;
if (score >= highscore) {
registerNewHighscore(highscore + 1);
}
goBack();
}
}

How do I change a color of a Html element in a canvas?

I have made a post on this before however, it was not in a canvas, but when you try to apply this to a canvas It gives an error along the lines of Cant change the color of undefined so I thought it was an error of the way I defined it so I would add it to a class then run it as changing the color of all elements in the class, but when I try it the canvas just disappears.. but getting to the point is there an easy way to change the color of a HTML element in a canvas or am I just crazy
Code
var myGamePiece = el.classList.add("class1");
var myObstacles = [];
var myScore;
function startGame() {
myGamePiece = new component(30, 30, "red", 10, 120);
myGamePiece.gravity = 0.05;
myScore = new component("30px", "Consolas", "black", 280, 40, "text");
myGameArea.start();
}
var myGameArea = {
canvas: document.createElement("canvas"),
start: function() {
this.canvas.width = 480;
this.canvas.height = 270;
this.context = this.canvas.getContext("2d");
document.body.insertBefore(this.canvas, document.body.childNodes[0]);
this.frameNo = 0;
this.interval = setInterval(updateGameArea, 20);
},
clear: function() {
this.context.clearRect(0, 0, this.canvas.width, this.canvas.height);
}
}
function component(width, height, color, x, y, type) {
this.type = type;
this.score = 0;
this.width = width;
this.height = height;
this.speedX = 0;
this.speedY = 0;
this.x = x;
this.y = y;
this.gravity = 0;
this.gravitySpeed = 0;
this.update = function() {
ctx = myGameArea.context;
if (this.type == "text") {
ctx.font = this.width + " " + this.height;
ctx.fillStyle = color;
ctx.fillText(this.text, this.x, this.y);
} else {
ctx.fillStyle = color;
ctx.fillRect(this.x, this.y, this.width, this.height);
}
}
this.newPos = function() {
this.gravitySpeed += this.gravity;
this.x += this.speedX;
this.y += this.speedY + this.gravitySpeed;
this.hitBottom();
}
this.hitBottom = function() {
var rockbottom = myGameArea.canvas.height - this.height;
if (this.y > rockbottom) {
this.y = rockbottom;
this.gravitySpeed = 0;
}
}
this.crashWith = function(otherobj) {
var myleft = this.x;
var myright = this.x + (this.width);
var mytop = this.y;
var mybottom = this.y + (this.height);
var otherleft = otherobj.x;
var otherright = otherobj.x + (otherobj.width);
var othertop = otherobj.y;
var otherbottom = otherobj.y + (otherobj.height);
var crash = true;
if ((mybottom < othertop) || (mytop > otherbottom) || (myright < otherleft) || (myleft > otherright)) {
crash = false;
}
return crash;
}
}
function updateGameArea() {
var x, height, gap, minHeight, maxHeight, minGap, maxGap;
for (i = 0; i < myObstacles.length; i += 1) {
if (myGamePiece.crashWith(myObstacles[i])) {
return;
}
}
myGameArea.clear();
myGameArea.frameNo += 1;
if (myGameArea.frameNo == 1 || everyinterval(150)) {
x = myGameArea.canvas.width;
minHeight = 20;
maxHeight = 200;
height = Math.floor(Math.random() * (maxHeight - minHeight + 1) + minHeight);
minGap = 50;
maxGap = 200;
gap = Math.floor(Math.random() * (maxGap - minGap + 1) + minGap);
myObstacles.push(new component(10, height, "green", x, 0));
myObstacles.push(new component(10, x - height - gap, "green", x, height + gap));
}
for (i = 0; i < myObstacles.length; i += 1) {
myObstacles[i].x += -1;
myObstacles[i].update();
}
myScore.text = "SCORE: " + myGameArea.frameNo;
myScore.update();
myGamePiece.newPos();
myGamePiece.update();
}
function everyinterval(n) {
if ((myGameArea.frameNo / n) % 1 == 0) {
return true;
}
return false;
}
function accelerate(n) {
myGamePiece.gravity = n;
}
function Test() {
document.getElementsByClassName("class1").style.background = "yellow";
}
canvas {
border: 1px solid #d3d3d3;
background-color: #f1f1f1;
}
.class1 {}
<body onload="startGame()">
<button onmousedown="accelerate(-0.2)" onmouseup="accelerate(0.05)">ACCELERATE</button>
<p> Credit To W3Schools.com </p>
<button onclick="test">Click To Change Player's Color</button>
</body>

The code starts with: var myGamePiece = el.classList.add("class1");el is not defined but anyway myGamePiece needs to be a component as created in startGame, it is not an ordinary HTML element.
It is the creation of that component that the color is set. Currently the color is hardcoded as 'red'. To change the color you need to set a variable, let's call it playerColor, and use that in the component creation call rather than 'red'.
You are using function test to set up a color so let's change the test function to do that, but you need to get that color set up before startGame otherwise the canvas will have the incorrect color for the piece (or no set color).
var playersColor = "red"; //the default value if the player doesn't change it
var myGamePiece;
var myObstacles = [];
var myScore;
function startGame() {
myGamePiece = new component(30, 30, playersColor, 10, 120);//use playersColor
myGamePiece.gravity = 0.05;
myScore = new component("30px", "Consolas", "black", 280, 40, "text");
myGameArea.start();
}
var myGameArea = {
canvas: document.createElement("canvas"),
start: function() {
this.canvas.width = 480;
this.canvas.height = 270;
this.context = this.canvas.getContext("2d");
document.body.insertBefore(this.canvas, document.body.childNodes[0]);
this.frameNo = 0;
this.interval = setInterval(updateGameArea, 20);
},
clear: function() {
this.context.clearRect(0, 0, this.canvas.width, this.canvas.height);
}
}
function component(width, height, color, x, y, type) {
this.type = type;
this.score = 0;
this.width = width;
this.height = height;
this.speedX = 0;
this.speedY = 0;
this.x = x;
this.y = y;
this.gravity = 0;
this.gravitySpeed = 0;
this.update = function() {
ctx = myGameArea.context;
if (this.type == "text") {
ctx.font = this.width + " " + this.height;
ctx.fillStyle = color;
ctx.fillText(this.text, this.x, this.y);
} else {
ctx.fillStyle = color;
ctx.fillRect(this.x, this.y, this.width, this.height);
}
}
this.newPos = function() {
this.gravitySpeed += this.gravity;
this.x += this.speedX;
this.y += this.speedY + this.gravitySpeed;
this.hitBottom();
}
this.hitBottom = function() {
var rockbottom = myGameArea.canvas.height - this.height;
if (this.y > rockbottom) {
this.y = rockbottom;
this.gravitySpeed = 0;
}
}
this.crashWith = function(otherobj) {
var myleft = this.x;
var myright = this.x + (this.width);
var mytop = this.y;
var mybottom = this.y + (this.height);
var otherleft = otherobj.x;
var otherright = otherobj.x + (otherobj.width);
var othertop = otherobj.y;
var otherbottom = otherobj.y + (otherobj.height);
var crash = true;
if ((mybottom < othertop) || (mytop > otherbottom) || (myright < otherleft) || (myleft > otherright)) {
crash = false;
}
return crash;
}
}
function updateGameArea() {
var x, height, gap, minHeight, maxHeight, minGap, maxGap;
for (i = 0; i < myObstacles.length; i += 1) {
if (myGamePiece.crashWith(myObstacles[i])) {
return;
}
}
myGameArea.clear();
myGameArea.frameNo += 1;
if (myGameArea.frameNo == 1 || everyinterval(150)) {
x = myGameArea.canvas.width;
minHeight = 20;
maxHeight = 200;
height = Math.floor(Math.random() * (maxHeight - minHeight + 1) + minHeight);
minGap = 50;
maxGap = 200;
gap = Math.floor(Math.random() * (maxGap - minGap + 1) + minGap);
myObstacles.push(new component(10, height, "green", x, 0));
myObstacles.push(new component(10, x - height - gap, "green", x, height + gap));
}
for (i = 0; i < myObstacles.length; i += 1) {
myObstacles[i].x += -1;
myObstacles[i].update();
}
myScore.text = "SCORE: " + myGameArea.frameNo;
myScore.update();
myGamePiece.newPos();
myGamePiece.update();
}
function everyinterval(n) {
if ((myGameArea.frameNo / n) % 1 == 0) {
return true;
}
return false;
}
function accelerate(n) {
myGamePiece.gravity = n;
}
function test() {
playersColor = "yellow";
}
<body>
<button onmousedown="accelerate(-0.2)" onmouseup="accelerate(0.05)">ACCELERATE</button>
<p> Credit To W3Schools.com </p>
<button onclick="test()">Click To Change Player's Color</button>
<button onclick="startGame();">Click to start the game</button>
</body>
...............................................................................
Although the following errors are not fundamentally what is causing non-changing of the player's color, they contain some coding errors which it might be helpful to point out for the future.
<button onclick="test">Click To Change Player's Color</button>
<script>
function Test() {
document.getElementsByClassName("class1").style.background = "yellow";
</script>
The onclick="test" does nothing - you may be confusing the structure element.onclick = test - which sets which function is run on the element being clicked - with the syntax for the onclick="test();" needed in the button element attributes.
A further error is that the function is called Test, not test. Javascript is case sensitive. Also you need to select the one element with class1, not retrieve a collection of such elements, so you can set its style (if that is useful, is it?).

A simple Javascript game called Traceball

I need help/advice on how to sort out an issue I have
https://raw.githubusercontent.com/TalvinJoshuaJacobs/TraceBall/master/src
My task is to code a game in Javascript and HTML where the user has to escape an enemy.
I am struggling with telling the the red box "obstacle" to follow me (the green box)
Any suggestions?
<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1.0"/>
<style>
canvas {
border:20px solid #000000;
background-color: #f1f1f1;
}
</style>
</head>
<body onload="startGame()">
<script>
var myGamePiece;
var myObstacle;
function startGame() {
myGamePiece = new component(130, 130, "green", 10, 120);
myObstacle = new component(130, 130, "red", 300, 120);
myGameArea.start();
}
var myGameArea = {
canvas : document.createElement("canvas"),
start : function() {
this.canvas.width = 1550;
this.canvas.height = 872;
this.canvas.style.cursor = "none";
this.context = this.canvas.getContext("2d");
document.body.insertBefore(this.canvas, document.body.childNodes[0]);
this.interval = setInterval(updateGameArea, 20);
window.addEventListener('mousemove', function (e) {
myGameArea.x = e.pageX;
myGameArea.y = e.pageY;
})
},
clear : function() {
this.context.clearRect(0, 0, this.canvas.width, this.canvas.height);
},
stop : function() {
clearInterval(this.interval);
}
}
function component(width, height, color, x, y) {
this.width = width;
this.height = height;
this.speedX = 0;
this.speedY = 0;
this.x = x;
this.y = y;
this.update = function() {
ctx = myGameArea.context;
ctx.fillStyle = color;
ctx.fillRect(this.x, this.y, this.width, this.height);
}
this.newPos = function() {
this.x += this.speedX;
this.y += this.speedY;
}
this.crashWith = function(otherobj) {
var myleft = this.x;
var myright = this.x + (this.width);
var mytop = this.y;
var mybottom = this.y + (this.height);
var otherleft = otherobj.x;
var otherright = otherobj.x + (otherobj.width);
var othertop = otherobj.y;
var otherbottom = otherobj.y + (otherobj.height);
var crash = true;
if ((mybottom < othertop) || (mytop > otherbottom) || (myright < otherleft) || (myleft > otherright)) {
crash = false;
}
return crash;
}
}
function updateGameArea() {
if (myGamePiece.crashWith(myObstacle)) {
myGameArea.stop();
} else {
myGameArea.clear();
if (myGameArea.x && myGameArea.y) {
myGamePiece.x = myGameArea.x;
myGamePiece.y = myGameArea.y;
}
myObstacle.x -= 5;
myObstacle.update();
myGamePiece.newPos();
myGamePiece.update();
}
}
</script>
<p>Avoid hitting the obstacle, or else the game will stop.</p>
</body>
</html>

If you're looking for implementation suggestions, you should look into event sourcing. You could make your game piece an event emitter and trigger an event that will move your obstacle when the event is fired.
If you're using a bundler like webpack or something similar you can use the nodejs EventEmitter, but that's not available in the browser by default.
https://www.npmjs.com/package/EventEmitter
Check out this repo for a naive implementation of an event emitter that can be used in the browser: https://github.com/parallaxisjones/microevent.js
<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1.0"/>
<style>
canvas {
border:20px solid #000000;
background-color: #f1f1f1;
}
</style>
</head>
<body onload="startGame()">
<script>
var myGamePiece;
var myObstacle;
function startGame() {
myGamePiece = new component(130, 130, "green", 10, 120);
myObstacle = new component(130, 130, "red", 300, 120);
myGamePiece.on('move', function(params){
// do something with myObstacle
myObstacle.updatePosition(params);
})
myGameArea.start();
}
var myGameArea = {
canvas : document.createElement("canvas"),
start : function() {
this.canvas.width = 1550;
this.canvas.height = 872;
this.canvas.style.cursor = "none";
this.context = this.canvas.getContext("2d");
document.body.insertBefore(this.canvas, document.body.childNodes[0]);
this.interval = setInterval(updateGameArea, 20);
window.addEventListener('mousemove', function (e) {
myGameArea.x = e.pageX;
myGameArea.y = e.pageY;
})
},
clear : function() {
this.context.clearRect(0, 0, this.canvas.width, this.canvas.height);
},
stop : function() {
clearInterval(this.interval);
}
}
function component(width, height, color, x, y) {
this.width = width;
this.height = height;
this.speedX = 0;
this.speedY = 0;
this.x = x;
this.y = y;
this.update = function() {
ctx = myGameArea.context;
ctx.fillStyle = color;
ctx.fillRect(this.x, this.y, this.width, this.height);
}
this.newPos = function() {
this.x += this.speedX;
this.y += this.speedY;
//fire an event that can be subscribed to by other things
this.trigger('move', this)
}
this.crashWith = function(otherobj) {
var myleft = this.x;
var myright = this.x + (this.width);
var mytop = this.y;
var mybottom = this.y + (this.height);
var otherleft = otherobj.x;
var otherright = otherobj.x + (otherobj.width);
var othertop = otherobj.y;
var otherbottom = otherobj.y + (otherobj.height);
var crash = true;
if ((mybottom < othertop) || (mytop > otherbottom) || (myright < otherleft) || (myleft > otherright)) {
crash = false;
}
return crash;
}
}
// register components as an event emitter with the microevent lib linked
MicroEvent.mixin(component)
function updateGameArea() {
if (myGamePiece.crashWith(myObstacle)) {
myGameArea.stop();
} else {
myGameArea.clear();
if (myGameArea.x && myGameArea.y) {
myGamePiece.x = myGameArea.x;
myGamePiece.y = myGameArea.y;
}
myObstacle.x -= 5;
myObstacle.update();
myGamePiece.newPos();
myGamePiece.update();
}
}
</script>
<p>Avoid hitting the obstacle, or else the game will stop.</p>
</body>
</html>

Canvas with HTML and JavaScript

In w3schools there is a basic game and I can't figure out how to make the piece or object a circle. I'm so confused and have tried everything but it didn't work. How can I use fill circle or another method for this? I'm new to canvas.
<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1.0"/>
<style>
canvas {
border:1px solid #d3d3d3;
background-color: #f1f1f1;
}
</style>
</head>
<body onload="startGame()">
<script>
var myGamePiece;
var myObstacles = [];
var myScore;
function startGame() {
myGamePiece = new component(30, 30, "red", 10, 120);
myGamePiece.gravity = 0.05;
myScore = new component("30px", "Consolas", "black", 280, 40,
"text");
myGameArea.start();
}
var myGameArea = {
canvas : document.createElement("canvas"),
start : function() {
this.canvas.width = 480;
this.canvas.height = 270;
this.context = this.canvas.getContext("2d");
document.body.insertBefore(this.canvas,
document.body.childNodes[0]);
this.frameNo = 0;
this.interval = setInterval(updateGameArea, 20);
},
clear : function() {
this.context.clearRect(0, 0, this.canvas.width,
this.canvas.height);
}
}
function component(width, height, color, x, y, type) {
this.type = type;
this.score = 0;
this.width = width;
this.height = height;
this.speedX = 0;
this.speedY = 0;
this.x = x;
this.y = y;
this.gravity = 0;
this.gravitySpeed = 0;
this.update = function() {
ctx = myGameArea.context;
if (this.type == "text") {
ctx.font = this.width + " " + this.height;
ctx.fillStyle = color;
ctx.fillText(this.text, this.x, this.y);
} else {
ctx.fillStyle = color;
ctx.fillRect(this.x, this.y, this.width, this.height);
}
}
this.newPos = function() {
this.gravitySpeed += this.gravity;
this.x += this.speedX;
this.y += this.speedY + this.gravitySpeed;
this.hitBottom();
}
this.hitBottom = function() {
var rockbottom = myGameArea.canvas.height - this.height;
if (this.y > rockbottom) {
this.y = rockbottom;
this.gravitySpeed = 0;
}
}
this.crashWith = function(otherobj) {
var myleft = this.x;
var myright = this.x + (this.width);
var mytop = this.y;
var mybottom = this.y + (this.height);
var otherleft = otherobj.x;
var otherright = otherobj.x + (otherobj.width);
var othertop = otherobj.y;
var otherbottom = otherobj.y + (otherobj.height);
var crash = true;
if ((mybottom < othertop) || (mytop > otherbottom) || (myright <
otherleft) || (myleft > otherright)) {
crash = false;
}
return crash;
}
}
function updateGameArea() {
var x, height, gap, minHeight, maxHeight, minGap, maxGap;
for (i = 0; i < myObstacles.length; i += 1) {
if (myGamePiece.crashWith(myObstacles[i])) {
return;
}
}
myGameArea.clear();
myGameArea.frameNo += 1;
if (myGameArea.frameNo == 1 || everyinterval(150)) {
x = myGameArea.canvas.width;
minHeight = 20;
maxHeight = 200;
height = Math.floor(Math.random()*(maxHeight-
minHeight+1)+minHeight);
minGap = 50;
maxGap = 200;
gap = Math.floor(Math.random()*(maxGap-minGap+1)+minGap);
myObstacles.push(new component(10, height, "green", x, 0));
myObstacles.push(new component(10, x - height - gap, "green", x,
height + gap));
}
for (i = 0; i < myObstacles.length; i += 1) {
myObstacles[i].x += -1;
myObstacles[i].update();
}
myScore.text="SCORE: " + myGameArea.frameNo;
myScore.update();
myGamePiece.newPos();
myGamePiece.update();
}
function everyinterval(n) {
if ((myGameArea.frameNo / n) % 1 == 0) {return true;}
return false;
}
function accelerate(n) {
myGamePiece.gravity = n;
}
</script>
<br>
<button onmousedown="accelerate(-0.2)"
onmouseup="accelerate(0.05)">ACCELERATE</button>
<p>Use the ACCELERATE button to stay in the air</p>
<p>How long can you stay alive?</p>
</body>
</html>

Change your function component() and startGame() to this one.
You can draw cirlce with arc method.
Details: https://www.w3schools.com/tags/canvas_arc.asp
function startGame() {
myGamePiece = new component(30, 30, "red", 10, 120, "player");
myGamePiece.gravity = 0.05;
myScore = new component("30px", "Consolas", "black", 280, 40,
"text");
myGameArea.start();
}
function component(width, height, color, x, y, type) {
this.type = type;
this.score = 0;
this.width = width;
this.height = height;
this.speedX = 0;
this.speedY = 0;
this.x = x;
this.y = y;
this.gravity = 0;
this.gravitySpeed = 0;
this.update = function() {
ctx = myGameArea.context;
ctx.fillStyle = color;
if (this.type == "text") { // text
ctx.font = this.width + " " + this.height;
ctx.fillStyle = color;
ctx.fillText(this.text, this.x, this.y);
} else if (this.type == "player") { // player
ctx.beginPath();
ctx.arc(this.x, this.y, 35,0,2*Math.PI);
ctx.fill();
ctx.stroke();
} else { // wall
ctx.fillStyle = color;
ctx.fillRect(this.x, this.y, this.width, this.height);
}
}
this.newPos = function() {
this.gravitySpeed += this.gravity;
this.x += this.speedX;
this.y += this.speedY + this.gravitySpeed;
this.hitBottom();
}
this.hitBottom = function() {
var rockbottom = myGameArea.canvas.height - this.height;
if (this.y > rockbottom) {
this.y = rockbottom;
this.gravitySpeed = 0;
}
}
this.crashWith = function(otherobj) {
var myleft = this.x;
var myright = this.x + (this.width);
var mytop = this.y;
var mybottom = this.y + (this.height);
var otherleft = otherobj.x;
var otherright = otherobj.x + (otherobj.width);
var othertop = otherobj.y;
var otherbottom = otherobj.y + (otherobj.height);
var crash = true;
if ((mybottom < othertop) || (mytop > otherbottom) || (myright <
otherleft) || (myleft > otherright)) {
crash = false;
}
return crash;
}
}

Can't figure out which event handler to use on phone for Javascript game

I have this little game in Javascript, It's sort of a rough replica of Flappy bird. It works well on desktops but on phones however, I can't seem to figure out which event handler to use with the button at the bottom to initiate the accelerate function.
When tried on phones, the button is clickable but there's no output.
<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1.0"/>
<style>
canvas {
border:1px solid #d3d3d3;
background-color: #f1f1f1;
}
</style>
</head>
<body onload="startGame()">
<script>
var myGamePiece;
var myObstacles = [];
var myScore;
function startGame() {
myGamePiece = new component(30, 30, "red", 10, 120);
myGamePiece.gravity = 0.05;
myScore = new component("30px", "Consolas", "black", 280, 40, "text");
myGameArea.start();
}
var myGameArea = {
canvas : document.createElement("canvas"),
start : function() {
this.canvas.width = 780;
this.canvas.height = 470;
this.context = this.canvas.getContext("2d");
document.body.insertBefore(this.canvas, document.body.childNodes[0]);
this.frameNo = 0;
this.interval = setInterval(updateGameArea, 20);
},
clear : function() {
this.context.clearRect(0, 0, this.canvas.width, this.canvas.height);
}
}
function component(width, height, color, x, y, type) {
this.type = type;
this.score = 0;
this.width = width;
this.height = height;
this.speedX = 0;
this.speedY = 0;
this.x = x;
this.y = y;
this.gravity = 0;
this.gravitySpeed = 0;
this.update = function() {
ctx = myGameArea.context;
if (this.type == "text") {
ctx.font = this.width + " " + this.height;
ctx.fillStyle = color;
ctx.fillText(this.text, this.x, this.y);
} else {
ctx.fillStyle = color;
ctx.fillRect(this.x, this.y, this.width, this.height);
}
}
this.newPos = function() {
this.gravitySpeed += this.gravity;
this.x += this.speedX;
this.y += this.speedY + this.gravitySpeed;
this.hitBottom();
}
this.hitBottom = function() {
var rockbottom = myGameArea.canvas.height - this.height;
if (this.y > rockbottom) {
this.y = rockbottom;
this.gravitySpeed = 0;
}
}
this.crashWith = function(otherobj) {
var myleft = this.x;
var myright = this.x + (this.width);
var mytop = this.y;
var mybottom = this.y + (this.height);
var otherleft = otherobj.x;
var otherright = otherobj.x + (otherobj.width);
var othertop = otherobj.y;
var otherbottom = otherobj.y + (otherobj.height);
var crash = true;
if ((mybottom < othertop) || (mytop > otherbottom) || (myright < otherleft) || (myleft > otherright)) {
crash = false;
}
return crash;
}
}
function updateGameArea() {
var x, height, gap, minHeight, maxHeight, minGap, maxGap;
for (i = 0; i < myObstacles.length; i += 1) {
if (myGamePiece.crashWith(myObstacles[i])) {
return;
}
}
myGameArea.clear();
myGameArea.frameNo += 1;
if (myGameArea.frameNo == 1 || everyinterval(150)) {
x = myGameArea.canvas.width;
minHeight = 20;
maxHeight = 200;
height = Math.floor(Math.random()*(maxHeight-minHeight+1)+minHeight);
minGap = 50;
maxGap = 200;
gap = Math.floor(Math.random()*(maxGap-minGap+1)+minGap);
myObstacles.push(new component(10, height, "green", x, 0));
myObstacles.push(new component(10, x - height - gap, "green", x, height + gap));
}
for (i = 0; i < myObstacles.length; i += 1) {
myObstacles[i].x += -1;
myObstacles[i].update();
}
myScore.text="SCORE: " + myGameArea.frameNo;
myScore.update();
myGamePiece.newPos();
myGamePiece.update();
}
function everyinterval(n) {
if ((myGameArea.frameNo / n) % 1 == 0) {return true;}
return false;
}
function accelerate(n) {
myGamePiece.gravity = n;
}
</script>
<br>
<button onmousedown="accelerate(-0.2)" onmouseup="accelerate(0.05)">ACCELERATE</button>
</body>
</html>