为什么Google控制台针对此简单的Java功能命令返回“未定义”？

Question

var polygon = turf.polygon([[[a, b], [c, d], [e, f], [g, h], [i, j], [k, l]]]);

var centroid = turf.centroid(polygon);

map.setView(new L.LatLng(x,y), 1);

Frog1Layer = L.geoJson(Frog1, { 
        style: {
            weight: 0.5,
            color: 'white',
            fillOpacity: 1,
            fillColor: 'red',
        }

}).addTo(map);


var frogIcon = L.icon({
iconUrl: 'frogIcon.png',

iconSize:     [30, 30],
iconAnchor:   [30, 30], 
popupAnchor:  [-3, -76]

L.marker([x,y], {icon: frogIcon}).bindPopup("I am a pop-up").addTo(map);

为什么在console.log（'My todos'，todos）;时返回“ undefined”；返回完美的输出？

https://watchandcode.com/courses/60264/lectures/928384

课程“显示待办事项应该具有功能”