Not really, .ts files can have types in the source code. .d.ts lets you type external JS code which is useful for untyped dependencies, as is the case here, I i

Not really, .ts files can have types in the source code. .d.ts lets you type external JS code which is useful for untyped dependencies, as is the case here, I imagine. But within your own project having types be part of the actual declarations is much better.