I work with PHP and JavaScript all the time. I have not seriously picked up a new programming language in 5 years (I started coding 6 years ago.) I build my projects with the frameworks based on those two languages.

Now, I am building a cross-platform mobile app for Craypolar. I tried React Native and now switched to Flutter.

Flutter is a framework based on Dart programming language. Both of them are from Google. The first thing anyone would do while learning a programming language is to get used to the syntax. At least that's what I do. I read the docs it's a good start. Although I should learn a few more new concepts to me like Generics, Collections, Async programming to build the app.