tsconfig.json

{
  "compilerOptions": {
    "target": "es2017",
    "module": "commonjs",
    "lib": [
      "es6"
    ],
    "allowJs": true,
    "outDir": "build",
    "rootDir": "src",
    "strict": true,
    "noImplicitAny": true,
    "esModuleInterop": true,
    "resolveJsonModule": true,
    "strictNullChecks": true /* When type checking, take into account `null` and `undefined`. */,
    "strictFunctionTypes": true /* When assigning functions, check to ensure parameters and the return values are subtype-compatible. */,
    "strictBindCallApply": true /* Check that the arguments for `bind`, `call`, and `apply` methods match the original function. */,
    "strictPropertyInitialization": true /* Check for class properties that are declared but not set in the constructor. */,
    "noImplicitThis": true,
    "experimentalDecorators": true /* Enable experimental support for TC39 stage 2 draft decorators. */,
    "emitDecoratorMetadata": true,
    "skipLibCheck": true /* Skip type checking all .d.ts files. */,
    "noImplicitReturns": true /* Enable error reporting for codepaths that do not explicitly return in a function. */,
    "noFallthroughCasesInSwitch": true,
    "noUnusedLocals": true /* Enable error reporting when a local variables aren't read. */,
    "noUnusedParameters": true,
    "alwaysStrict": true,
    "types": [
      "node",
      "jest"
    ],
    "typeRoots": [
      "node_modules/@types"
    ]
  },
  "include": [
    "src/**/*.ts" /* Include every ts file in source folder */
  ],
  "exclude": [
    "node_modules" /* exclude everything in  node_modules */
  ]
}