Shared objects and methods between Dart and JavaScript

我想直接使用let a =new Class();的方式，不使用module，并且可以直接使用 a.method();有没有实现的办法或者思路，在flutter中做哪些工作

I want to use let a = new Class(); directly, without using module, and can directly use a.method(); Is there any way or idea to achieve it, what work is done in flutter