Javascript just offers a simple alert box without any customisation. With the code below u can call a VBscript function from javascript witch makes it possible to create your own alert box with or without an icon.
Javascript function

NS4 = (document.layers);
IE4 = (document.all);
ver4 = (NS4 || IE4);

function newAlert(title,mess,icon,mods) {
(IE4) ? makeMsgBox(title,mess,icon,0,0,mods) : alert(mess);
}

VBScript function

Function makeMsgBox(tit,mess,icons,buts,defs,mods)
butVal = buts + (icons*16) + (defs*256) + (mods*4096)
makeMsgBox = MsgBox(mess,butVal,tit)
End Function

Call the new alert box

newAlert(”title”,”msg”,0,0);