Well, since you assigned it to a variable in the console, the undefined looks
correct as a response. You could do:
window.testLat = SimVar.GetSimVarValue("PLANE LATITUDE", "degree latitude");
window.testLat
In the console, and that should give you your lat back. My guess is that in
this case above, the BonanzaElement HTMLElement is actually mounted to the DOM
before the script elements are (or something like that), and thus the JS is
not yet fully loaded when you get to connectedCallback. You may need to add an
event listener to something like DOMContentLoaded to ensure all the JS is
loaded before trying to set up your update cycle. -Matt