Well, of course TS is a superset of JS so any TS developer should be comfortable in JS.
You say “algorithm test”. What do you mean by that?
Do you mean just logging onto a algorithm test site? I see that leetcode offers a TS option, I imagine others do too.
Do you mean an employment test? That depends. Some of the employment tests I have done have asked me what language I would want to use - the algorithm is usually the same regardless. Some have assumed I would be testing in JS because that is what they use. If you are looking for a job, I would recommend practicing both, just to be ready.
I have just started learning TS and like it a lot, but I think I’d still want to use JS in a timed test - less typing.