Map.forEach usage

main.dart

void main() {
  Map<String, List> menuData = {
    "food": [
      {"title": "火腿堡", "price": 35.0, "count": 0},
      {"title": "香雞堡", "price": 40.0, "count": 0}
    ],
    "drink": [
      {"title": "鮮奶茶", "price": 30.0, "count": 0},
      {"title": "咖啡", "price": 35.0, "count": 0}
    ]
  };
  
  List orders = [];
  menuData.forEach((String k, List v) {
  	orders += v;
  });
  
  print(orders);
}

View in DartPad:
https://dartpad.dartlang.org/98ea049a8465840c46ec33e1634537a6