Listing 4.8

3rdparty-Listing4-8.js

function makeRequest(url, method) {
            var xhr;
            if (typeof XMLHttpRequest === "undefined") {
                return null;
            }

            xhr = new XMLHttpRequest();
            if ("withCredentials" in xhr) {
                xhr.open(method, url, true);
                return xhr;
            };

            if (typeof XDomainRequest === "undefined") {
                return null;
            }

            xhr = new XDomainRequest();
            xhr.open(method, url);
            return xhr;
        }