1.dart in the map and js in the map
DART map and js like a simple object, but still not the same, dart to get through under standard element attributes map [subscript], but you can not use the map. Subscript, because the dart in the map is the map, it is the object. js in the map is a simple object.
2.dart of json serialization.
dart in execution json serialization, serialized only direct map, can not be directly serialized object, the object to develop toJson method, and the return value of this method is a map, using currently perfect json serialization languages are php, php because js associative array is a list and map combination.