Firework Effect

<!--Paste this code before the </head> tag-->

<script type="text/javascript">
// <![CDATA[
var bits=80; // how many bits
var speed=33; // how fast - smaller is faster
var bangs=5; // how many can be launched simultaneously (note that using too many can slow the script down)
var colours=new Array("#03f", "#f03", "#0e0", "#93f", "#0cf", "#f93", "#f0c");
// blue red green purple cyan orange pink

/****************************
* Fireworks Effect *
*(c)2004-11 mf2fm web-design*
* http://www.mf2fm.com/rv *
* DON'T EDIT BELOW THIS BOX *
****************************/
var bangheight=new Array();
var intensity=new Array();
var colour=new Array();
var Xpos=new Array();
var Ypos=new Array();
var dX=new Array();
var dY=new Array();
var stars=new Array();
var decay=new Array();
var swide=800;
var shigh=600;
var boddie;

window.onload=function() { if (document.getElementById) {
var i;
boddie=document.createElement("div");
boddie.style.position="fixed";
boddie.style.top="0px";
boddie.style.left="0px";
boddie.style.overflow="visible";
boddie.style.width="1px";
boddie.style.height="1px";
boddie.style.backgroundColor="transparent";
document.body.appendChild(boddie);
set_width();
for (i=0; i<bangs; i++) {
write_fire(i);
launch(i);
setInterval('stepthrough('+i+')', speed);
}
}}

function write_fire(N) {
var i, rlef, rdow;
stars[N+'r']=createDiv('|', 12);
boddie.appendChild(stars[N+'r']);
for (i=bits*N; i<bits+bits*N; i++) {
stars[i]=createDiv('*', 13);
boddie.appendChild(stars[i]);
}
}

function createDiv(char, size) {
var div=document.createElement("div");
div.style.font=size+"px monospace";
div.style.position="absolute";
div.style.backgroundColor="transparent";
div.appendChild(document.createTextNode(char));
return (div);
}

function launch(N) {
colour[N]=Math.floor(Math.random()*colours.length);
Xpos[N+"r"]=swide*0.5;
Ypos[N+"r"]=shigh-5;
bangheight[N]=Math.round((0.5+Math.random())*shigh*0.4);
dX[N+"r"]=(Math.random()-0.5)*swide/bangheight[N];
if (dX[N+"r"]>1.25) stars[N+"r"].firstChild.nodeValue="/";
else if (dX[N+"r"]<-1.25) stars[N+"r"].firstChild.nodeValue="\\";
else stars[N+"r"].firstChild.nodeValue="|";
stars[N+"r"].style.color=colours[colour[N]];
}

function bang(N) {
var i, Z, A=0;
for (i=bits*N; i<bits+bits*N; i++) {
Z=stars[i].style;
Z.left=Xpos[i]+"px";
Z.top=Ypos[i]+"px";
if (decay[i]) decay[i]--;
else A++;
if (decay[i]==15) Z.fontSize="7px";
else if (decay[i]==7) Z.fontSize="2px";
else if (decay[i]==1) Z.visibility="hidden";
Xpos[i]+=dX[i];
Ypos[i]+=(dY[i]+=1.25/intensity[N]);
}
if (A!=bits) setTimeout("bang("+N+")", speed);
}

function stepthrough(N) {
var i, M, Z;
var oldx=Xpos[N+"r"];
var oldy=Ypos[N+"r"];
Xpos[N+"r"]+=dX[N+"r"];
Ypos[N+"r"]-=4;
if (Ypos[N+"r"]<bangheight[N]) {
M=Math.floor(Math.random()*3*colours.length);
intensity[N]=5+Math.random()*4;
for (i=N*bits; i<bits+bits*N; i++) {
Xpos[i]=Xpos[N+"r"];
Ypos[i]=Ypos[N+"r"];
dY[i]=(Math.random()-0.5)*intensity[N];
dX[i]=(Math.random()-0.5)*(intensity[N]-Math.abs(dY[i]))*1.25;
decay[i]=16+Math.floor(Math.random()*16);
Z=stars[i];
if (M<colours.length) Z.style.color=colours[i%2?colour[N]:M];
else if (M<2*colours.length) Z.style.color=colours[colour[N]];
else Z.style.color=colours[i%colours.length];
Z.style.fontSize="13px";
Z.style.visibility="visible";
}
bang(N);
launch(N);
}
stars[N+"r"].style.left=oldx+"px";
stars[N+"r"].style.top=oldy+"px";
}

window.onresize=set_width;
function set_width() {
var sw_min=999999;
var sh_min=999999;
if (document.documentElement && document.documentElement.clientWidth) {
if (document.documentElement.clientWidth>0) sw_min=document.documentElement.clientWidth;
if (document.documentElement.clientHeight>0) sh_min=document.documentElement.clientHeight;
}
if (typeof(self.innerWidth)!="undefined" && self.innerWidth) {
if (self.innerWidth>0 && self.innerWidth<sw_min) sw_min=self.innerWidth;
if (self.innerHeight>0 && self.innerHeight<sh_min) sh_min=self.innerHeight;
}
if (document.body.clientWidth) {
if (document.body.clientWidth>0 && document.body.clientWidth<sw_min) sw_min=document.body.clientWidth;
if (document.body.clientHeight>0 && document.body.clientHeight<sh_min) sh_min=document.body.clientHeight;
}
if (sw_min==999999 || sh_min==999999) {
sw_min=800;
sh_min=600;
}
swide=sw_min;
shigh=sh_min;
}
// ]]>
</script>