<script type="text/javascript">
function init() {
var ctx = document.getElementById('stars').getContext('2d')
ctx.fillStyle = "#827839"
ctx.shadowColor="#000000"
ctx.shadowOffsetX=6
ctx.shadowOffsetY=6
ctx.shadowBlur=9
ctx.beginPath()
ctx.moveTo(15, 150)
ctx.lineTo(100,140)
ctx.lineTo(170,90)
ctx.lineTo(230,140)
ctx.lineTo(315,150)
ctx.lineTo(230,200)
ctx.lineTo(300,263)
ctx.lineTo(170,233)
ctx.lineTo(30,263)
ctx.lineTo(100,200)
ctx.closePath()
ctx.fill()
}
window.addEventListener('load', init, false)
</script>
<canvas id="stars" width="333" height="300">
Your browser does not support the canvas element .
</canvas>
这个由浏览器默认设定，不同的浏览器不一样，有的浏览器是黑色圆点，有的浏览器是星号，不可以修改。除非你自己用代码实现这样的功能，没有说哪个属性或样式一设置就可以这么简单。自己实现可以用js的replace或者用html5的placeholder之类的东西来实现。思路是将用户输入的东西复制到另外一个隐藏元素中。同时修改可见的输入框的内容。
html5特效代码旋转的星空，首先要设置背景为暗一点的背景色或者图片，例如设置成黑色的背景颜色，然后把代码复制到html文件里，设置下下方JS里的一些设置，如星星的数量、星星移动的范围、星星的大小等，保存后用支持html5的浏览器打开就能看到旋转的星空特效。温馨提示：如果使用复制按钮代码出现错误，建议使用ctrl+c来复制代码。
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>旋转的星空</title>
<style type="text/css">
body{background: blackpadding: 0margin: 0overflow:hidden}
.header{margin: 0 autowidth: 100%height: 100%background-color: #000position: relative}
</style>
</head>
<body>
<div class="header"><canvas id="canvas"></canvas></div>
<script>
var canvas = document.getElementById('canvas'),
ctx = canvas.getContext('2d'),
w = canvas.width = window.innerWidth,
h = canvas.height = window.innerHeight,
hue = 217,
stars = [],
count = 0,
maxStars = 3000//星星数量
var canvas2 = document.createElement('canvas'),
ctx2 = canvas2.getContext('2d')
canvas2.width = 100
canvas2.height = 100
var half = canvas2.width / 2,
gradient2 = ctx2.createRadialGradient(half, half, 0, half, half, half)
gradient2.addColorStop(0.025, '#CCC')
gradient2.addColorStop(0.1, 'hsl(' + hue + ', 61%, 33%)')
gradient2.addColorStop(0.25, 'hsl(' + hue + ', 64%, 6%)')
gradient2.addColorStop(1, 'transparent')
ctx2.fillStyle = gradient2
ctx2.beginPath()
ctx2.arc(half, half, half, 0, Math.PI * 2)
ctx2.fill()
// End cache
function random(min, max) {
if (arguments.length <2) {
max = min
min = 0
}
if (min >max) {
var hold = max
max = min
min = hold
}
return Matwww.scxhdzs.com#or(Math.random() * (max - min + 1)) + min
}
function maxOrbit(x, y) {
var max = Math.max(x, y),
diameter = Math.round(Math.sqrt(max * max + max * max))
return diameter / 2
//星星移动范围，值越大范围越小，
}
var Star = function() {
this.orbitRadius = random(maxOrbit(w, h))
this.radius = random(60, this.orbitRadius) / 8
//星星大小
this.orbitX = w / 2
this.orbitY = h / 2
this.timePassed = random(0, maxStars)
this.speed = random(this.orbitRadius) / 50000
//星星移动速度
this.alpha = random(2, 10) / 10
count++
stars[count] = this
}
Star.prototype.draw = function() {
var x = Math.sin(this.timePassed) * this.orbitRadius + this.orbitX,
y = Math.cos(this.timePassed) * this.orbitRadius + this.orbitY,
twinkle = random(10)
if (twinkle === 1 &&this.alpha >0) {
this.alpha -= 0.05
} else if (twinkle === 2 &&this.alpha <1) {
this.alpha += 0.05
}
ctx.globalAlpha = this.alpha
ctx.drawImage(canvas2, x - this.radius / 2, y - this.radius / 2, this.radius, this.radius)
this.timePassed += this.speed
}
for (var i = 0i <maxStarsi++) {
new Star()
}
function animation() {
ctx.globalCompositeOperation = 'source-over'
ctx.globalAlpha = 0.5//尾巴
ctx.fillStyle = 'hsla(' + hue + ', 64%, 6%, 2)'
ctx.fillRect(0, 0, w, h)
ctx.globalCompositeOperation = 'lighter'
for (var i = 1, l = stars.lengthi <li++) {
stars[i].draw()
}
window.requestAnimationFrame(animation)
}
animation()
</script>
</body>
</html>
