m// JavaScript source code
// setup canvas
var canvas = document.querySelector('canvas');
var ctx = canvas.getContext('2d');
var width = canvas.width = window.innerWidth;
var height = canvas.height = window.innerHeight;
var para = document.querySelector('p');
// ballcount variable
var ballCount = 0;
// function to generate random number
function random(min, max) {
var num = Math.floor(Math.random() * (max - min)) + min;
return num;
}
// function to display ball count on screen
function displayBallCount() {
para.textContent = 'Ball Count: ' + ballCount;
}
//Shape constructor function
function Shape(x, y, velX, velY, exists) {
this.x = x;
this.y = y;
this.velX = velX;
this.velY = velY;
this.exists = exists;
}
//Ball constructor function
function Ball(x, y, velX, velY, exists, color, size) {
Shape.call(this, x, y, velX, velY, exists);
this.color = color;
this.size = size;
}
// Ball prototype and constructor
Ball.prototype = Object.create(Shape.prototype);
Ball.prototype.constructor = Ball;
//Ball prototype methods
Ball.prototype.draw = function () {
ctx.beginPath();
ctx.fillStyle = this.color;
ctx.arc(this.x, this.y, this.size, 0, 2 * Math.PI);
ctx.fill();
displayBallCount();
}
Ball.prototype.update = function () {
if ((this.x + this.size) >= width) {
this.velX = -(this.velX);
}
if ((this.x - this.size) <= 0) {
this.velX = -(this.velX);
}
if ((this.y + this.size) >= height) {
this.velY = -(this.velY);
}
if ((this.y - this.size) <= 0) {
this.velY = -(this.velY);
}
this.x += this.velX;
this.y += this.velY;
}
Ball.prototype.collisionDetect = function () {
for (var j = 0; j < balls.length; j++) {
if (!(this === balls[j])) {
var dx = this.x - balls[j].x;
var dy = this.y - balls[j].y;
var distance = Math.sqrt(dx * dx + dy * dy);
if (distance < this.size + balls[j].size) {
balls[j].color = this.color = 'rgb(' + random(0, 255) + ',' + random(0, 255) + ',' + random(0, 255) + ')';
}
}
}
}
// EvilCircle constructor function
function EvilCircle(x, y, exists) {
Shape.call(this, x, y, exists);
this.color = 'white';
this.size = 10;
this.velX = 20;
this.velY = 20;
}
//EvilCircle prototype and constructor
EvilCircle.prototype = Object.create(Shape.prototype);
EvilCircle.prototype.constructor = EvilCircle;
// EvilCircle prototype methods
EvilCircle.prototype.draw = function () {
ctx.beginPath();
ctx.stokeStyle = this.color;
ctx.lineWidth = 3;
ctx.arc(this.x, this.y, this.size, 0, 2 * Math.PI);
ctx.stroke();
}
EvilCircle.prototype.checkBounds = function () {
if ((this.x + this.size) >= width) {
this.x -= this.size;
}
if ((this.x - this.size) <= 0) {
this.x += this.size;
}
if ((this.y + this.size) >= height) {
this.y -= this.size;
}
if ((this.y - this.size) <= 0) {
this.y += this.size;
}
}
EvilCircle.prototype.setControls = function () {
var _this = this;
window.onkeydown = function (e) {
if (e.keyCode === 65) {
_this.x -= _this.velX;
} else if (e.keyCode === 68) {
_this.x += _this.velX;
} else if (e.keyCode === 87) {
_this.y -= _this.velY;
} else if (e.keyCode === 83) {
_this.y += _this.velY;
}
}
}
EvilCircle.prototype.collisionDetect = function () {
for (var j = 0; j < balls.length; j++) {
if (balls[j].exists) {
var dx = this.x - balls[j].x;
var dy = this.y - balls[j].y;
var distance = Math.sqrt(dx * dx + dy * dy);
if (distance < this.size + balls[j].size) {
balls[j].exists = false;
ballCount--;
displayBallCount();
}
}
}
}
var balls = []; // Balls array
var evilCircle = new EvilCircle(random(0, width), random(0, height), true);
evilCircle.setControls();
// function to run program. name: loop
function loop() {
ctx.fillStyle = 'rgba(0, 0, 0, 0.25)';
ctx.fillRect(0, 0, width, height);
while (balls.length < 25) {
var ball = new Ball(
random(0, width),
random(0, height),
random(-7, 7),
random(-7, 7),
true,
'rgb(' + random(0, 255) + ',' + random(0, 255) + ',' + random(0, 255) + ')',
random(10, 20)
);
balls.push(ball);
ballCount++;
}
for (var i = 0; i < balls.length; i++) {
if (balls[i].exists) {
balls[i].draw();
balls[i].update();
balls[i].collisionDetect();
}
}
evilCircle.draw();
evilCircle.checkBounds();
evilCircle.collisionDetect();
requestAniationFrame(loop);
}
loop();
Try on stackoverflow where you can find too many developers that can help you on that.
Here we talk about webdev for mozilla stuff