Query Person or Group Field.js

// BEGIN PERSON OR GROUP QUERY
    
    // Queery Person or Group Properties
    function getItemDetails(webUrl,listTitle,itemId,selectFields, expandFields){
        var endpointUrl = webUrl + "/_api/web/lists/getbytitle('" + listTitle + "')/items(" + itemId + ")";
        endpointUrl+= '?$select=' + selectFields.join(",");
        endpointUrl+= '&$expand=' + expandFields.join(",");
        return executeRequest(endpointUrl,'GET');
    }


    function executeRequest(url,method,headers,payload) 
    {
        if (typeof headers == 'undefined'){
            headers = {};
        }
        headers["Accept"] = "application/json;odata=verbose";
        if(method == "POST") {
            headers["X-RequestDigest"] = $("#__REQUESTDIGEST").val();
        }   

        var ajaxOptions = 
        {       
           url: url,   
           type: method,  
           contentType: "application/json;odata=verbose",
           headers: headers
        };
        if(method == "POST") {
          ajaxOptions.data = JSON.stringify(payload);
        }  

        return $.ajax(ajaxOptions);
    }



    var webUrl = _spPageContextInfo.webAbsoluteUrl;
    var selectFields = [
            "Project_x0020_Manager/Title","Implementing_x0020_Partner/Title",
            "Project_x0020_Owner/Title", "StartDate", "EndDate", "Created",
            "Project_x0020_Sponsor","Project_x0020_Name"
        ];
    var expandFields = [
        'Project_x0020_Manager','Implementing_x0020_Partner',
        'Project_x0020_Owner'
    ];
    
    function cleandates(dates) {
        return String.format("{0:d}",new Date(dates));
    };

    getItemDetails(webUrl,'ProjectDetailsList', 1,selectFields,expandFields)
        .done(function(data){
            
         // Populat the UI ASAP
        $('#project_name').html(data.d.Project_x0020_Name);
        $('#project_start_date').html(cleandates(data.d.StartDate));
        $('#project_enddate').html(cleandates(data.d.EndDate));
        $('#project_mger').html(data.d.Implementing_x0020_Partner.Title);
        $('#implement_mger').html(data.d.Implementing_x0020_Partner.Title);
        $('#project_sponsor').html(data.d.Project_x0020_Sponsor);
        $('#project_owner').html(data.d.Project_x0020_Owner.Title);
        
        console.log("Project Owner ID: "+data.d.Project_x0020_Owner);
        
    })
    .fail(function(jqXHR, textStatus, errorThrown) {
        var resp = JSON.parse(jqXHR.responseText);
        var message = resp ? resp.error.message.value : textStatus;
        alert("Error: "+ message);
     });
    
    
    // END PERSON OR GROUP QUERY