There are 5 types of events: "ready" -- happens when the API Sandbox has fully loaded the state of the game. No parameters passed to callback. "chat:message" -- happens when anything is sent to chat. 1st parameter passed to callback is a message object that contains details of what was sent and how it was processed. "add:<TYPE>" -- happens when a new object of <TYPE> is created. 1st parameter is the new object (which might be pretty useless, depending on the type...) "change:<TYPE>" -- happens when an object of <TYPE> is updated. This is usually by a player (API doesn't trigger most events), but is sometimes follow on modifications from creation of an object (particularly graphic objects). 1st parameter is the object that was changed (with the changes having already taken place), 2nd parameter is a simple javascript object with the prior state of the object. "change:<TYPE>:<PROPERTY>" -- you can also specify a property you want to be notified about. Note that you need to use the _ on the front of read only names for this. "destroy:<TYPE>" -- happens when an object of <TYPE> is removed. 1st parameter is the object that is being removed in it's current state. There is no event for UI stuff like onClick or isSelected. The API runs on a server far removed from where the game is running. It only observes the state of the game via the backend database, and makes changes to that. Very much "action at a distance." The only place you can know about selected objects is as part of a chat event. Here are some good starter links for API: <a href="https://app.roll20.net/forum/post/6605115/namespaces-novice-seeks-help-exploring-the-revealing-module-pattern" rel="nofollow">https://app.roll20.net/forum/post/6605115/namespaces-novice-seeks-help-exploring-the-revealing-module-pattern</a> <a href="https://app.roll20.net/forum/post/6584105/creating-an-object-that-holds-specific-character-dot-id-and-character-name/?pagenum=1" rel="nofollow">https://app.roll20.net/forum/post/6584105/creating-an-object-that-holds-specific-character-dot-id-and-character-name/?pagenum=1</a> <a href="https://app.roll20.net/forum/post/6237754/slug%7D" rel="nofollow">https://app.roll20.net/forum/post/6237754/slug%7D</a> <a href="https://www.youtube.com/watch?v=jam2yx8btaQ" rel="nofollow">https://www.youtube.com/watch?v=jam2yx8btaQ</a>