TypeScript makes your interfaces and their documentation much more explicit than with vanilla JS. If you work on your code in a team, you actually want to very clearly document the inputs and outputs of your functions and the types of your data structures. Doing this with JSDocs is cumbersome and error prone in my experience and actually more work than just using TypeScript.
Having explicit types with TypeScript helps both machines (better / safer refactoring) and the humans to reason about the code.
So the bit of extra effort to add the types is very well invested. And keep in mind that developers spend much more time reading code than writing it.
Comments
Just to add an aspect that I haven't seen so far.
TypeScript makes your interfaces and their documentation much more explicit than with vanilla JS. If you work on your code in a team, you actually want to very clearly document the inputs and outputs of your functions and the types of your data structures. Doing this with JSDocs is cumbersome and error prone in my experience and actually more work than just using TypeScript.
Having explicit types with TypeScript helps both machines (better / safer refactoring) and the humans to reason about the code.
So the bit of extra effort to add the types is very well invested. And keep in mind that developers spend much more time reading code than writing it.