求小于某数的素数，JS

<script language=javascript>

var num1=100;
var result="";
var flag=1;
for(var i=4;i<num1;i++)
{
for(var j=2;j<=Math.sqrt(i);j++)
{
if(i%j==0)
{
flag=0;
}

}
if(flag==1)
{
result+=i+",";

}
flag=1;
}
document.write("2,3,"+result.substring(0,result.length-1));

</script>