帮我用javascript写一个爱心的程序

好的，以下是用 JavaScript 实现爱心程序的代码：

function loveHeart(x, y) {
  this.x = x;
  this.y = y;
  this.timer = 0;
  this.alive = true;
  this.ctx = ctx;

  this.move = function() {
    var step = this.timer / 100;
    var x = 16 * Math.pow(Math.sin(step), 3);
    var y = -(13 * Math.cos(step) - 5 * Math.cos(2 * step) - 2 * Math.cos(3 * step) - Math.cos(4 * step));
    this.x += x;
    this.y += y;
    this.timer++;
    if(this.y > canvas.height) {
      this.alive = false;
    }
  };

  this.draw = function() {
    ctx.save();
    ctx.beginPath();
    ctx.fillStyle = '#FF69B4';
    var x = this.x + 25;
    var y = this.y + 25;
    ctx.moveTo(x, y);
    ctx.bezierCurveTo(x, y-30, x+50, y-30, x+50, y);
    ctx.bezierCurveTo(x+50, y+60, x, y+90, x-50, y);
    ctx.bezierCurveTo(x-50, y-30, x, y-30, x, y);
    ctx.fill();
    ctx.restore();
  };
};

var canvas = document.createElement('canvas');
canvas.width = 500;
canvas.height = 500;
document.body.appendChild(canvas);
var ctx = canvas.getContext('2d');
var hearts = [];
setInterval(function() {
  var heart = new loveHeart(Math.random() * 500 - 25, -50);
  hearts.push(heart);
}, 500);

(function drawFrame() {
  requestAnimationFrame(drawFrame);
  ctx.clearRect(0, 0, canvas.width, canvas.height);
  hearts.forEach(function(heart) {
    heart.move();
    heart.draw();
  });
  hearts = hearts.filter(function(heart) { return heart.alive; });
})();

这段代码可以在网页中显示一个飘落的粉色爱心，效果如下所示：