See the sibling comment from oblosys for an example where the exact same code can give different results in vanilla JS vs after a tsc pass. As you can see there

See the sibling comment from oblosys for an example where the exact same code can give different results in vanilla JS vs after a tsc pass. As you can see there, the problem is that an identifier can simultaneously represent a value and a type. This is different than JSX or hashbang, where the set of non-JS syntax cannot legally overlap with existing syntax/semantics.