Get Record's User Security Roles in CRM 2015 using Javascript

Get Record's User Security Roles in CRM 2015 using Javascript

function GetUserRoles() {
    var roles = Xrm.Page.context.getUserRoles();

    for (var i = 0; i < roles.length; i++) {
        GetRole(roles[i]);
    }
}

function GetRole(roleid) {
    var serverUrl = Xrm.Page.context.getClientUrl();
    var oDataSelect = serverUrl + "/XRMServices/2011/OrganizationData.svc/RoleSet?$select=Name&$filter=RoleId eq guid'" + roleid + "'";

    var retrieveReq = new XMLHttpRequest();
    retrieveReq.open("GET", oDataSelect, false);
    retrieveReq.setRequestHeader("Accept", "application/json");
    retrieveReq.setRequestHeader("Content-Type", "application/json;charset=utf-8");
    retrieveReq.onreadystatechange = function () {
        GetRoleData(this);
    };
    retrieveReq.send();
}

function GetRoleData(retrieveReq) {
    if (retrieveReq.readyState == 4) {
        if (retrieveReq.status == 200) {
            var retrieved = JSON.parse(retrieveReq.responseText).d;
            if(retrieved.results[0].Name="System Administrator")
            {
            Xrm.Page.getAttribute("cms_showdialogbutton").setValue(0);
            }
            else
            {
            Xrm.Page.getAttribute("cms_showdialogbutton").setValue(1);
            }
            alert(retrieved.results[0].Name);//Security Role Name
        }
    }
}