Usando ciclo For:
<meta charset="UTF-8">
<h1>Numero parez del 1 al 100</h1>
<script>
function jumpLine(){
document.write("<br><br><br>");
}
function print(phrase){
document.write(phrase);
jumpLine();
}
function isPar(number){
return number%2==0;
}
for(var i=1;i<=100;i++){
if(isPar(i)){
print(i);
}
}
</script>