Open multiple window on page load with JavaScript

<script type="text/javascript">
function performCalc(url) {
var randomnumber = Math.floor((Math.random()*100)+1);
window.open(url,"_blank",'PopUp'+randomnumber+',scrollbars=1,menubar=0,resizable=1,width=100,height=100');
}

for (i = 0; i < 5; i++) {
var url ='www.'+i+'.com';
performCalc(url);
}          
</script>