Because Dart isn't a viable option for writing libraries or frameworks which are meant to be used from JavaScript. You can interact with JS libraries, but expo

Because Dart isn't a viable option for writing libraries or frameworks which are meant to be used from JavaScript. You can interact with JS libraries, but exposing some API to JS-land is a completely different matter. There are some vague plans to improve this, but there hasn't been much interest, because if you use Dart anyways, you do of course want to use it as the "host" language. It has the tooling and all that jazz. Of course you'd want to use it for as much as you can.