tsconfig.json

{
  "$schema": "http://json.schemastore.org/tsconfig",

  "compilerOptions": {
    "allowSyntheticDefaultImports": true,
    "alwaysStrict": true,
    "declaration": true,
    "declarationMap": true,
    "esModuleInterop": true,
    "forceConsistentCasingInFileNames": true,
    "inlineSources": true,
    "moduleResolution": "node",
    "noImplicitAny": true,
    "outDir": "built",
    "preserveSymlinks": false,
    "removeComments": true,
    "resolveJsonModule": true,
    "skipLibCheck": true,
    "sourceMap": true,
    "strict": true,
    "strictNullChecks": true,
    "module": "es6",
    "lib": ["es6", "dom"],
    "target": "es6",
    "types": ["node", "jest", "webpack-env"],
    "jsx": "react"
  },
  "include": ["src"],
  "exclude": ["built"]
}