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JS烟花背景效果实现方法

2015-03-03 00:00 627 查看

本文实例讲述了JS烟花背景效果实现方法。分享给大家供大家参考。具体实现方法如下：

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">

<head>

<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />

<title>又一个很酷的JS烟花背景特效</title>

<script type="text/javascript">

var fireworks = function(){

 this.size = 20;

 this.rise();

}

fireworks.prototype = {

 color:function(){

  var c = ['0','3','6','9','c','f'];

  var t = [c[Math.floor(Math.random()*100)%6],'0','f'];

  t.sort(function(){return Math.random()>0.5?-1:1;});

  return '#'+t.join('');

 },

 aheight:function(){

  var h = document.documentElement.clientHeight-250;

  return Math.abs(Math.floor(Math.random()*h-200))+201;

 },

 firecracker:function(){

  var b = document.createElement('div');

  var w = document.documentElement.clientWidth;

  b.style.position = 'absolute';

  b.style.color = this.color();

  b.style.bottom = 0;

  b.style.left = Math.floor(Math.random()*w)+1+'px';

  document.body.appendChild(b);

  return b;

 },

 rise:function(){

  var o = this.firecracker();

  var n = this.aheight();

  var c = this.color;

  var e = this.expl;

  var s = this.size;

  var k = n;

  var m = function(){

   o.style.bottom = parseFloat(o.style.bottom)+k*0.1+'px';

   k-=k*0.1;

   if(k<2){

    clearInterval(clear);

    e(o,n,s,c);

   }

  }

  o.innerHTML = '.';

  if(parseInt(o.style.bottom)<n){

   var clear = setInterval(m,20);

  }

 },

 expl:function(o,n,s,c){

  var R=n/3,Ri=n/6,Rii=n/9;

  var r=0,ri=0,rii=0;

  for(var i=0;i<s;i++){

   var span = document.createElement('span');

   var p = document.createElement('i');

   var a = document.createElement('a');

   span.style.position = 'absolute';

   span.style.fontSize = n/10+'px';

   span.style.left = 0;

   span.style.top = 0;

   span.innerHTML = '*';

   p.style.position = 'absolute';

   p.style.left = 0;

   p.style.top = 0;

   p.innerHTML = '*';

   a.style.position = 'absolute';

   a.style.left = 0;

   a.style.top = 0;

   a.innerHTML = '*';

   o.appendChild(span);

   o.appendChild(p);

   o.appendChild(a);

  }

  function spr(){

   r += R*0.1;

   ri+= Ri*0.06;

   rii+= Rii*0.06;

   sp = o.getElementsByTagName('span');

   p = o.getElementsByTagName('i');

   a = o.getElementsByTagName('a');

   for(var i=0; i<sp.length;i++){

    sp[i].style.color = c();

    p[i].style.color = c();

    a[i].style.color = c();

    sp[i].style.left=r*Math.cos(360/s*i)+'px';

    sp[i].style.top=r*Math.sin(360/s*i)+'px';

    sp[i].style.fontSize=parseFloat(sp[i].style.fontSize)*0.96+'px';

    p[i].style.left=ri*Math.cos(360/s*i)+'px';

    p[i].style.top=ri*Math.sin(360/s*i)+'px';

    p[i].style.fontSize=parseFloat(sp[i].style.fontSize)*0.96+'px';

    a[i].style.left=rii*Math.cos(360/s*i)+'px';

    a[i].style.top=rii*Math.sin(360/s*i)+'px';

    a[i].style.fontSize=parseFloat(sp[i].style.fontSize)*0.96+'px';

   }

   R-=R*0.1;

   if(R<2){

    o.innerHTML = '';

    o.parentNode.removeChild(o);

    clearInterval(clearI);

   }

  }

  var clearI = setInterval(spr,20);

 }

}

window.onload = function(){

 function happyNewYear(){

  new fireworks();

 }

 setInterval(happyNewYear,1000);

}

</script>

<style type="text/css">

</style>

</head>

<body style="background:#000;font:12px Georgia, 'Times New Roman', Times, serif">

</body>

</html>

运行效果如下所示：

希望本文所述对大家的javascript程序设计有所帮助。

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