Earlier quoted context omitted.
Typescript is superior for refactoring.
How? I think it’s inferior because it allows you to rewrite only parts, and unless you convert your entire code base, then you’ll not have type safety. Because the bits that aren’t typescript won’t warn you when you compile.
We write all our new code in good ol ES6 flavor of JavaScript and typehint in jsdoc. Typescript as a typechecker serves as very well.
It’s a great incremental adoption strategy.