以下是一个使用JavaScript和CSS3实现的简易版新年快乐全屏满天星动画特效的示例代码：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>New Year Celebration</title>
<style>
body, html {
margin: 0;
padding: 0;
height: 100%;
}
.stars {
width: 100%;
height: 100%;
position: fixed;
top: 0;
left: 0;
z-index: 1;
pointer-events: none;
opacity: 0.5;
}
</style>
</head>
<body>
<canvas class="stars"></canvas>
<script>
const canvas = document.querySelector('.stars');
const ctx = canvas.getContext('2d');
let stars = [];
function init() {
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
for (let i = 0; i < 200; i++) {
stars.push(new Star());
}
animate();
}
function animate() {
ctx.fillStyle = 'black';
ctx.fillRect(0, 0, canvas.width, canvas.height);
for (let i = 0; i < stars.length; i++) {
stars[i].update();
stars[i].draw(ctx);
}
requestAnimationFrame(animate);
}
function Star() {
this.x = Math.random() * canvas.width;
this.y = Math.random() * canvas.height;
this.size = Math.random() * 2;
this.speed = Math.random() * 0.05;
this.update = function() {
this.x -= this.speed;
if (this.x < -5) this.x = canvas.width;
this.y -= this.speed;
if (this.y < -5) this.y = canvas.height;
};
this.draw = function(ctx) {
ctx.fillStyle = 'white';
ctx.beginPath();
ctx.arc(this.x, this.y, this.size, 0, 2 * Math.PI);
ctx.fill();
};
}
window.onload = init;
window.onresize = init;
</script>
</body>
</html>这段代码创建了一个全屏的画布，并在其中生成了随机的白色星星。星星随机生成、随机移动、随机大小。画布的尺寸会随着窗口大小的变化而变化，保持全屏。这个简易版本的动画特效可以作为新年快乐的视觉装饰，也可以作为创建更复杂动画的基础示例。