Comment by WorldMaker

Node directly runs Typescript now, just not inside libraries (for political reasons not technical ones). It's type stripping approach is the strictest compared to Deno/Bun in that you must turn on a bunch of Typescript linting like Isolated Modules and Erasable Syntax Only to get it to work (and not use enums or namespaces). (Which is in line with the strictness suggested by the Type Annotations TC-39 proposal, for what it is worth.)