tsconfig.json

{
  "compilerOptions": {
    "esModuleInterop": true,
    "allowSyntheticDefaultImports": true,
    "strict": true,
    "strictNullChecks": true,
    "strictFunctionTypes": true,
    "noImplicitThis": true,
    "alwaysStrict": true,
    "noUnusedLocals": true,
    "noUnusedParameters": true,
    "noImplicitReturns": true,
    "noFallthroughCasesInSwitch": true,
    "noImplicitAny": true,
    "importHelpers": true,
    "isolatedModules": true,
    "target": "es6",
    "moduleResolution": "node",
    "lib": ["dom", "es5", "scripthost", "es2015.collection", "es2015.symbol", "es2015.iterable", "es2015.promise"],
    "types": ["node", "jest"],
    "typeRoots": ["./node_modules/@types"],
    "jsx": "react"
  }
}