The Window.onuserproxymity property represents an EventHandler, that is a function to be called when the userproximity event occurs. These events are of type UserProximityEvent and occur when the the device sensor detects that an object becomes nearby.
document.load() is a part of an old version of the W3C DOM Level 3 Load & Save module. Can be used with document.async to indicate whether the request is synchronous or asynchronous (the default). As of at least Gecko 1.9, this no longer supports cross-site loading of documents (Use XMLHttpRequest instead).