You actually don't, that's the nice part. NPM Typescript modules are shipped as transpiled js modules with d.ts files. Those d.ts files contain the type informations for consuming TS projects but they are completely optional and you can simply ignore them if you write a plain js project.

You can see this in the babel project, for example. It is written in typescript but used by a lot of js projects that don't care (and don't have to care) about this.