https://seekerswiki.com/Questions/meteor/How-to-migrate-from-Java-Script-to-Type-Script/40

I have an existing meteor project built with blaze and javascript. Is there any quick way that I can migrate my Javascript to Typescript?

Quick way? Probably not.

However, JavaScript is a proper subset of TypeScript. If you like, you can think of JavaScript as TypeScript, but without explicit typing, so you can do this incrementally. There are Meteor typings you could use to help you on the way.