for (i = 0; i < 2500; i++){
var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
//do Something
}
};
xhttp.open("GET", "http://localhost:63091/api/CustomerSite/GetSiteList?accessToken=123456789", true);
xhttp.send();
}