The vast majority of developers have strong misconceptions about how types work in programming languages, and especially how they work in JS. A tidal wave of interest in the broader JS community has begun to shift to “static typing” approaches, using type-aware tooling like TypeScript or Flow.

But I don’t agree at all that the inevitable conclusion of this is to decide JS’s type mechanism is bad and that we need to cover up JS’s types with solutions outside the language. We don’t have to follow the “static typing” way to be smart and solid with types in our programs. There are other options, if you’re just willing to go against the grain of the crowd, and with the grain of JS (again, more on that to come).

Even if you love TypeScript/Flow, you are not going to get the most out of those tools or coding approaches if you aren’t deeply familiar with how the language itself manages value types.

Without learning this pillar, your foundation in JS is shaky and incomplete at best.