foo.ts

interface Window {
  Promise: PromiseConstructor;
}

declare var require: {
    (path: string): any;
    <T>(path: string): T;
    (paths: string[], callback: (...modules: any[]) => void): void;
    ensure: (paths: string[], callback: (require: <T>(path: string) => T) => void) => void;
};

declare var fetch: any;

declare var module: any;