I did this to learn JS and React Native and it let me get started quickly, but wow was my code horrible. It was a good year before I stopped doing really stupid things in JS, because I only ever had learned enough JS to "Get Things Done".

This was in stark contrast to how I learned Java and C#, I deep dived into the internals of the languages and their runtimes (and at one point even worked on a version of the .NET CLR!), and all the code I wrote was in a mindset where I was cognizant of exactly what the runtime was doing to my code, how memory layout looked, how the GC works, and so on and so forth.

I would've spent a year being 100% more productive if I'd spent just another week or two learning JS properly.