User Typescript without .ts file directly in js

[chiqui3d]

I like to follow a pattern in programming languages and I would like to start using the typing of functions and variables in Javascript, but I do not understand why they force to use a different extension like .ts, is there any way to do it directly in .js?

[AlCalzone]

First of all: This question is better asked on StackOverflow. This is a bug tracker, not a support forum (as you read when creating this request)

Second: You can use JSDoc comments in plain JavaScript to assert the types of your methods and variables and just let TypeScript check those (for example by using VSCode as an editor). This is limited compared to full TypeScript but goes a long way already.

[joeytwiddle]

This isn't possible right now, but people have been asking for it, so maybe one day... #9694