帮我用javascript写一个烟花功能

好的，下面是一个简单的烟花效果的JavaScript代码，你可以将其放置在HTML文件中：

<canvas id="fireworks"></canvas>

// 获取画布对象
const canvas = document.getElementById('fireworks');
const ctx = canvas.getContext('2d');

// 设置画布的大小
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;

// 定义烟花的颜色
const colors = [
  '#FF4136', '#0074D9', '#2ECC40', '#FFDC00',
  '#FF851B', '#B10DC9', '#01FF70', '#F012BE'
];

// 定义烟花的粒子数
const particles = [];

// 定义烟花的构造函数
function Firework() {
  this.x = Math.random() * canvas.width;
  this.y = canvas.height;
  this.color = colors[Math.floor(Math.random() * colors.length)];
  this.radius = 4;
  this.velocity = {
    x: Math.random() * 6 - 3,
    y: Math.random() * 3 + 2
  };
  this.gravity = 0.1;
}

// 更新烟花的位置
Firework.prototype.update = function() {
  this.x += this.velocity.x;
  this.y -= this.velocity.y;
  this.velocity.y -= this.gravity;
};

// 绘制烟花
Firework.prototype.draw = function() {
  ctx.beginPath();
  ctx.arc(this.x, this.y, this.radius, 0, Math.PI * 2);
  ctx.fillStyle = this.color;
  ctx.fill();
};

// 创建烟花粒子
function createParticles(x, y) {
  for (let i = 0; i < 30; i++) {
    const particle = new Particle(x, y);
    particles.push(particle);
  }
}

// 定义烟花粒子的构造函数
function Particle(x, y) {
  this.x = x;
  this.y = y;
  this.color = colors[Math.floor(Math.random() * colors.length)];
  this.radius = Math.random() * 2;
  this.velocity = {
    x: Math.random() * 6 - 3,
    y: Math.random() * 6 - 3
  };
  this.gravity = 0.1;
  this.alpha = 1;
}

// 更新烟花粒子的位置
Particle.prototype.update = function() {
  this.x += this.velocity.x;
  this.y += this.velocity.y;
  this.velocity.y += this.gravity;
  this.alpha -= 0.01;
};

// 绘制烟花粒子
Particle.prototype.draw = function() {
  ctx.beginPath();
  ctx.arc(this.x, this.y, this.radius, 0, Math.PI * 2);
  ctx.fillStyle = this.color;
  ctx.globalAlpha = this.alpha;
  ctx.fill();
};

// 渲染烟花效果
function render() {
  ctx.clearRect(0, 0, canvas.width, canvas.height);

  if (Math.random() < 0.05) {
    const firework = new Firework();
    createParticles(firework.x, firework.y);
  }

  particles.forEach((particle, index) => {
    particle.update();
    particle.draw();

    if (particle.alpha <= 0) {
      particles.splice(index, 1);
    }
  });

  requestAnimationFrame(render);
}

render();

这个代码会在画布上随机生成多个烟花，并且烟花会爆炸成多个颜色不同的粒子。你可以尝试修改代码中的参数，例如烟花的粒子数、颜色等，来实现不同的效果。