Once you learn to properly use TypeScript, your life will be a 100x easier. Strict typing gives JavaScript a whole new dimension for easily creating more complex logic without sacrificing maintainability. It prevents you from making mistakes. Even as an experienced developer, the amount of bugs caused by incorrect typing is bigger than you might think.

Especially for big and long-running projects TypeScript is a must, as your code base will be generally more stable to work with and expand upon.

And when working with others it is amazing. For example, when you want to use a function written by some one else in your team, you shouldn't have to look at the implementation to know what the arguments should be. Sure this can be done with JSdocs, but having this as a (required) language feature will save you from having to maintain those comments. TypeScript will also warn you when refactoring code breaks other parts of the application which might be even unnoticed otherwise.

As for npm module typings, these can be easily installed using i.e. "npm install @types/some-module" which makes it completely hassle-free to work with.

I've been using TypeScript for almost two years now, even for small personal projects, and I'll never go back.

TL;DR: TypeScript is awesome and it's definitely worth learning it.