<meta charset="utf-8">
<script type="text/javascript">
function pulaLinha() {
document.write("<br>");
document.write("<br>");
}
function mostra(frase) {
document.write(frase);
pulaLinha();
}
var cont = 20;
while(cont >= 0){
mostra(cont);
cont = cont -1;
}
mostra("FIM");
</script>