Nested configuration

The TypeScript compiler is able to re-use a tsconfig.json file in another directory when compiling code in the current directory. This feature is handy if we would like to override a compiler option when running tsc within a specific directory. The tsconfig.json file uses the "extends" option for this purpose. As an example of this nested configuration, consider the following source tree:

├── sub1
│   ├── SampleJsFile.js
│   └── tsconfig.json
├── SampleTsFile.ts
└── tsconfig.json

Here, we have a tsconfig.json file in the project root directory, as well as a TypeScript file named SampleTsFile.ts. We also have a subdirectory named sub1 that contains a tsconfig.json file, and a JavaScript file named SampleJsFile.js. The tsconfig.json file in the project root directory is as follows:

{
    "compilerOptions": {
   ...