<SCRIPT LANGUAGE="javascript"> 
<!-- 
function banner(imgSource,url,alt,chance) { 
this.imgSource = imgSource; 
this.url = url; 
this.alt = alt; 
this.chance = chance; 
} 
function dispBanner() { 
with (this) document.write("<A HREF=" + url + "><IMG SRC="'"" + imgSource + "' WIDTH="720" HEIGHT="244" BORDER="0" ALT="'"" + alt + "'></A>"); 
} 
banner.prototype.dispBanner = dispBanner; 
banners = new Array(); 

banners[0] = new banner("http://www.dermatologia.net/novo/imagens/header01.jpg", 
"", 
"Banner 1", 
10); 
banners[1] = new banner("http://www.dermatologia.net/novo/imagens/header02.jpg", 
"", 
"Banner 2", 
10); 
banners[2] = new banner("http://www.dermatologia.net/novo/imagens/header03.jpg", 
"", 
"Banner 3", 
10); 
banners[3] = new banner("http://www.dermatologia.net/novo/imagens/header04.jpg", 
"", 
"Banner 4", 
10); 

sum_of_all_chances = 0; 
for (i = 0; i < banners.length; i++) { 
sum_of_all_chances += banners[1].chance; 
} 
function randomBanner() { 
chance_limit = 0; 
randomly_selected_chance = Math.round((sum_of_all_chances - 1) * Math.random()) + 1; 
for (i = 0; i < banners.length; i++) { 
chance_limit += banners[1].chance; 
if (randomly_selected_chance <= chance_limit) { 
document.write("<A HREF=" + banners[1].url + "><IMG SRC="'"" + banners[1].imgSource + "' WIDTH="720" HEIGHT="244" BORDER="0" ALT="'"" + banners[1].alt + "'></A>"); 
return banners[1]; 
break; 
} 
} 
} 
// End --> 
</SCRIPT>


