@Julia T , here are some important things that you need to know is that when your app is out in the real world...
1. There is a delay (however small) between when an action is taken on the browser, when the xojo code runs in your app and then when the result of that code appears back on the browser. It’s what we call “round trip” and it depends on network traffic, how physically far a user is from your app and among other things, how long it takes for your app to respond. The result is that you’re going to have to think asynchronously when designing.
2. Remember that there are multiple users accessing the app at the same time. Any properties that you want to be unique to a particular user should be attached to the Session object because each user/browser combination gets an instance of the Session class. Any properties attached to App or a Module will be global to all users.
3. You’ll need to be very careful not to create circular references up and down the Session structure. For instance, Session hierarchy looks like this:
It’s very important that the lower items don’t refer directly to the higher ones (like having a reference to Session in a Page). If you do, the Session and it’s contents will never be destroyed, even when a user leaves your app. If you need such functionality, you’ll need to use WeakRefs.
I’m sure there are others, but those are three big ones that we hear about a lot.