I wonder what went wrong, all that came up was a blank page. The browser controller displays an error: ‘main.js:97 Uncaught TypeError: Object.creat is not a function’
but I cannot fix it.
Here is my code…
// 定义弹球计数变量
const para = document.querySelector(‘p’);
let count = 0;
// 设置画布
const canvas = document.querySelector(‘canvas’);
const ctx = canvas.getContext(‘2d’);
const width = canvas.width = window.innerWidth;
const height = canvas.height = window.innerHeight;
// 生成随机数的函数
function random(min,max) {
const num = Math.floor(Math.random() * (max - min)) + min;
return num;
}
function randomColor() {
return ‘rgb(’ +
random(0, 255) + ', ’ +
random(0, 255) + ', ’ +
random(0, 255) + ‘)’;
}
function Shape(x, y, velX, velY,exists) {
this.x = x;
this.y = y;
this.velX = velX;
this.velY = velY;
this.exists = exists;
}
// 定义 Ball 构造器，继承自 Shape
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 = Object.create(Shape.prototype);
Ball.prototype.constructor = Ball;
// 定义彩球绘制函数
Ball.prototype.draw = function() {
ctx.beginPath();
ctx.fillStyle = this.color;
ctx.arc(this.x, this.y, this.size, 0, 2 * Math.PI);
ctx.fill();
};
//碰墙后折回
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;
};
//添加碰撞检测
Ball.prototype.collisionDetect = function() {
for (var j = 0; j < balls.length; j++) {
if (this !== balls[j]) {
const dx = this.x - balls[j].x;
const dy = this.y - balls[j].y;
const distance = Math.sqrt(dx * dx + dy * dy);
if (distance < this.size + balls[j].size) {
balls[j].color = this.color = randomColor();
}
}
}
};
// 定义 EvilCircle 构造器, 继承自 Shape
function EvilCircle(x, y, exists){
Shape.call(this, x, y, 20, 20, exists);
this.color=‘white’;
this.size = 10;
}
EvilCircle.prototype = Object.creat(Shape.prototype);
EvilCircle.prototype.constructor = EvilCircle;
// 定义 EvilCircle 绘制方法
EvilCircle.prototype.draw=function(){
ctx.beginPath();
ctx.lineWidth = 3;
ctx.strokeStyle = this.color;
ctx.arc(this.x, this.y, this.size, 0, 2 * Math.PI);
ctx.stroke();
};
// 定义 EvilCircle 的边缘检测（checkBounds）方法
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;
}
};
// 定义 EvilCircle 控制设置（setControls）方法
EvilCircle.prototype.setControls=function(){
window.onkeydown = e => {
switch(e.key) {
case ‘a’:
this.x -= this.velX;
break;
case ‘d’:
this.x += this.velX;
break;
case ‘w’:
this.y -= this.velY;
break;
case ‘s’:
this.y += this.velY;
break;
}
};
};
// 定义 EvilCircle 冲突检测函数balls[j].exists
EvilCircle.prototype.collisionDetect = function() {
for (let j = 0; j < balls.length; j++) {
if (balls[j].exists) {
const dx = this.x - balls[j].x;
const dy = this.y - balls[j].y;
const distance = Math.sqrt(dx * dx + dy * dy);
if (distance < this.size + balls[j].size) {
balls[j].exists = false;
count--;
para.textContent = '剩余彩球数：' + count;
}
}
}
};
//让球动起来
//首先我们需要一个地方储存小球，下面的数组会干这件事
const balls = [];
while (balls.length < 25) {
const size = random(10, 20);
let ball = new Ball(
// 为避免绘制错误，球至少离画布边缘球本身一倍宽度的距离
random(0 + size, width - size),
random(0 + size, height - size),
random(-7, 7),
random(-7, 7),
true,
randomColor(),
size
);
balls.push(ball);
count++;
para.textContent = ‘剩余彩球数：’ + count;
}
//几乎所有的动画效果都会用到一个运动循环
let evil = new EvilCircle(random(0, width), random(0, height), true);
evil.setControls();
function loop() {
ctx.fillStyle = ‘rgba(0, 0, 0, 0.25)’;
ctx.fillRect(0, 0, width, height);
for (let i = 0; i < balls.length; i++) {
if(balls[i].exists){
balls[i].draw();
balls[i].update();
balls[i].collisionDetect();
}
}
evil.draw();
evil.checkBounds();
evil.collisionDetect();
requestAnimationFrame(loop);
}
//让动画开始运行的话我们需要调用这个函数
loop();
