Never used dart until about a month ago for Flutter. Really loving it so far - like a better typescript. So many cool language features.
One good example I like to point to is the idea of mixins.
Take a look at how Dart does it here: https://dart.dev/language/mixins
Then take a look at TypeScript here: https://www.typescriptlang.org/docs/handbook/mixins.html
You might also be interested in this https://dart.dev/resources/coming-from/js-to-dart