onKeysAdded(obj, handler)

Register an event handler on the Map-like object obj to trigger when a new key or keys are set on obj. obj must implement @@can.onKeysAdded to be compatible with can-reflect.onKeysAdded. The function passed as handler will receive an Array of Strings as its one argument.

var obj = new DefineMap({ foo: "bar" });
canReflect.onKeysAded(obj, function(newKeys) {
    console.log(newKeys);
});

foo.set("baz", "quux");  // -> logs '["baz"]'