用javascript输出费波纳茨数列的前三十个数，请大神帮忙补齐代码

<script language="javascript">
var f1=_____，f2=_____;
var number=2;
document.write("<pre>";
document.write(f1+"\t"+f2"\t");
while(number<30)
{
number++;
f3=______;
document.write(f3+"\t");
if(number%10==0)
document.write("<br>");
_______;
_______;
}
document.write("</pre>");
</script>