Web API in MS CRM 2016

//Used to set Line of Business on create of Account record (Fetch LOB from the User Entity)

function onLoadSetLineOfBusiness(LineofBusiness) {

    var logInUser = Xrm.Page.context.getUserId();

    var retrieveRecordsReq = new XMLHttpRequest();

    var serverUrl = Xrm.Page.context.getClientUrl();

    // Adjust URL for differences between on premise and online

    if (serverUrl.match(/\/$/)) { serverUrl = serverUrl.substring(0, serverUrl.length - 1); }

    //Web API Calls

    var req = new XMLHttpRequest();

    if (logInUser != null && logInUser != "") {

        req.open("GET", Xrm.Page.context.getClientUrl() + "/api/data/v8.0/systemusers?$select=_new_lineofbusiness_value&$filter=systemuserid eq " + logInUser.replace('{', '').replace('}', '') + "", true);

        req.setRequestHeader("OData-MaxVersion", "4.0");

        req.setRequestHeader("OData-Version", "4.0");

        req.setRequestHeader("Accept", "application/json");

        req.setRequestHeader("Content-Type", "application/json; charset=utf-8");

        req.setRequestHeader("Prefer", "odata.include-annotations=\"OData.Community.Display.V1.FormattedValue\"");

        req.onreadystatechange = function () {

            if (this.readyState === 4) {

                req.onreadystatechange = null;

                if (this.status === 200) {

                    var LOBName = JSON.parse(this.response);

                    if (LOBName.value.length > 0) {

                        //to set the LookUp Value we have to use Formatted Value

                        if (LOBName.value[0]._new_lineofbusiness_value != null && LOBName.value[0]._new_lineofbusiness_value != "") {

                            var LOBvalue = new Array();

                            LOBvalue[0] = new Object();

                            LOBvalue[0].id = LOBName.value[0]._new_lineofbusiness_value;

                            LOBvalue[0].name = LOBName.value[0]['_new_lineofbusiness_value@OData.Community.Display.V1.FormattedValue'];

                            LOBvalue[0].entityType = "new_business";

                            Xrm.Page.getAttribute(LineofBusiness).setValue(LOBvalue);

                            Xrm.Page.getAttribute(LineofBusiness).setSubmitMode("always");

                        }

                    }

                }

                else {

                    alert(this.statusText);

                }

            }

        };

        req.send();

    }

}