TS1148 ~ How to "import" with --module: "none" and typescript 2.x

Question

I'm currently working on a project with some legacy javascript. The application does not include a module loader, it just puts everything as a global into the window object. Touching the legacy code and including a module loader is sadly not a viable option for me.

I want to use typescript for my own code. I set the typescript compiler-option

module : "none"

in my tsconfig.json and I only used namespaces to organize my own code. Worked well so far.

.. until now:

import * as Rx from 'rxjs';
..
Rx.Observable.from(['foo',bar']);
...
// Results in TypeScript-Error: 
//   TS1148:Cannot use imports, exports, or module augmentations when '--module' is 'none'. 

With the "module-none" option set, you can't use import statements in your typescript.
How can you include external libs with this typescript setup?
Is it even possible?

What I tried so far (to include Rx from the RxJs-Library)

///<reference path="../node_modules/rxjs/Rx.d.ts" />
..
Rx.Observable.from(['foo',bar']);
...
// Results in TypeScript-Error -> TS2304:Cannot find name 'Rx'. 

In this Related Question, Kirill Dmitrenko sugested using an reference-tag, didn´t work for me.

I ended up with this construct.

declare const Rx: any;

Works, but you loose type-checks and intellisense :(

Answer 1

Create a global declaration for Rx which is the type of the RxJS exports, like so:

import * as RxJS from "rxjs";

declare global {
    const Rx: typeof RxJS;
}

export {};

Save it to a file (e.g. global.d.ts) and then add that to the include array of tsconfig.json.