There are lots of mobile framework based on Javascript like React native, JQuery mobile, etc. And they are work great, but then it is still took time to developing it from start to finish, hard to learn, and the look isn't quite good, like native app. Now come Flutter, the framework for the future of mobile app development.

Their Tagline is quite impressive and sounds promising: "Flutter allows you to build beautiful native apps on iOS and Android from a single code base." Yes within flutter you can build cross platform mobile app that can run on Android, IOS and may be the future OS like Fuschia OS, since the framework and the OS itself is made and developed by Google themselves.

Choosing Flutter as your main tool is gonna be great decision, because i believe this is gonna be a big think in the future, and if you are one of them the first to know and have a skill on it, it's gonna be big advantage for you. Now, if you are interesting to try learn or even start working using Flutter, you can read some documentation on their official web https://flutter.io/.