Do you use TypeScript with projects only you will touch?

Of course. If you come back to a project in a couple of months, you will be very pleased you wrote some types and interfaces around your classes/functions. You probably come back for a quick refactor, tada!, this is now super trivial and you are probably done much faster and can go out for a drink with your friends instead of starting up the debugger.

For my TS is not my default option because most of the projects I start is for solving a problem I currently have and I need to advance fast. But if is a short project like a library that I am starting with TS to build the habit and not getting bored.

I'm on early phase of typescript use. I wittingly change my default - hobby - languages from JS to TS. That process sometimes faces some difficulty, on the contrary definitions part is really help, even middle sized project.

But sometimes I found TS is don't really understund every JS declaration.

For example:

interface Message { 
  id:string; 
  msg: string; 
  name?: string;
  avatar?: string;
}

type TBlogMap = (content:Message, index:number, list:Message[]) => Message;

// JS is fine but TS dosent know the ...rest part - which is obviously: {id, msg}
export const blogSameUserHeaderMap:TBlogMap 
= ({name, avatar, ...rest}, index, postList) => postList?.[index - 1]?.name === name
  ? {...rest}
  : {name, avatar, ...rest}
;

// working version
export const blogSameUserHeaderMap:TBlogMap 
= (content, index, postList) => postList?.[index - 1]?.name === content?.name
  ? ({msg:content.msg, id: content.id})
  : content
;

Why would you not start with TS? Just copy paste a tsconfig into your JS project and tada now its a TS project

JSdoc with minimal typescript to utilized the typehint and lint for personal project since i work with other language as well and it makes more sense to me. eg: ruby YARD, python docstring, dart doc comments, javadoc.

Sure, typing is kind of a documentation and a safety net at the same time. Usually the projects who were not "worth the effort" to be initialized with it, are the ones that are timewasters anyway - especially if you have plenty of boilerplates available to make the setup super fast🙂

Sure, the code could have less errors and you could read it in the future and still understand your code (before smile and rewrite it 😉)

No chance I'd use TypeScript on smaller things, can't be bothered to type all the extra bloat if only I or a few people will work on it.

Trying to. I like maintaining good habits, as they are hard to form in the first place. I am liable to use my indicators when I'm the only one on the road too, though, so I'm just weird 😁

I personally don't see the benefits at all - personal project or otherwise

Always, unless it's literally a 10 line scratch file to test something.

I find that on anything I work on that is non-trivial, it's much easier to take the time to get the TS right on object types and function inputs and output, and then use the type system later when I consume those same types. It means less mental overhead for me, and ultimately I move faster as a result.

I see a lot of people taking issue with the need to write out interfaces and types. I find that using the type inference system and utility types that TS provides gets me around about 80% of that, so in the end I'm really only specifying types for function inputs and that's about it. Output types are inferred, so if I make a breaking change in a function the TS compiler yells at me where I use it, and I know to fix the issue or fix it where it's implemented.