How To Structure Extensions Within An AMD TypeScript Program

I am writing a program in TypeScript that mainly follows an AMD loading pattern whereby classes are loaded using an import statement.

import TestRunner = require('../TS/TestRunner');

I do, however, want to include some extension methods that extend objects such as NodeList - so there will be a small number of extension files that contain an extension to the lib.d.ts interfaces and then an implementation of the additional feature - for example...

interface NodeList {
    extensionMethod(...info): NodeList;
}

NodeList.prototype.extensionMethod = function (...info: string[]) {
    return this;
};

I could just include all the extensions at the start of my program so they are available - but I would actually like to load them on demand just like the rest of the code. The problem is, the file containing the extensions doesn't really export anything to use - it just adds this code to existing objects.

What is the best way to include the extensions in my TypeScript program?

Solution

Here's a setup that works. Key points:

You'll need to place the interface extensions in a file that is not an external module (otherwise you'll be declaring a new interface in the external module scope rather than extending the existing type).
This only works on objects defined at the global scope. Extending other objects' prototypes is dangerous enough already, so no big loss on that account.
You'll need to manually invoke require. For AMD scenarios, use the undocumented /// <amd-depdendency path="path" /> tag.
The file containing the extensions can be an external module if needed.

myExtensions.d.ts

// In case you're not using node.d.ts
declare var process: process;

interface process {
    getFour: any;
}

extensions.ts

/// <reference path="myExtensions.d.ts" />

process.getFour = () => 4;

consumer.ts

/// <reference path="myExtensions.d.ts" />

// In case you're not using node.d.ts
declare var require;

// Manual import of extensions
require('./extensions');

console.log(process.getFour()); // Works