I have a node/typescript project structured like so:
- node_modules // => these are loaded npm/package.json
- src
  - node_modules // => shared modules for my project, not on npm
    - lib.ts
  - app.ts
- package.json
I have a secondary node_modules folder for my private packages mainly so I can import them from anywhere in my project and not have to worry about relative paths (as suggested here) on imports.
This works great because instead of import * as lib from '../../lib' or var lib = require('../../lib'), I can import * as lib from 'lib'.
Typescript compiles/loads lib w/o problem, but VS Code intellisense complains that it "cannot find module 'lib'".
FWIW, here is my tsconfig.json
{
  "compilerOptions": {
    "experimentalDecorators": false,
    "emitDecoratorMetadata": false,
    "module": "commonjs",
    "target": "es2015",
    "rootDir": "src"
  }
}
 
    