tsconfig.json

{
  "include": ["src"],
  "exclude": ["node_modules", "**/__tests__/*"],

  "compilerOptions": {
    "lib": [
      "es7"
    ],
    "target": "es6",
    "module": "commonjs",
    "declaration": true,
    "outDir": "./build",
    "strict": true,

    "allowJs": false,                       /* Allow javascript files to be compiled. */
    "sourceMap": false,                     /* Generates corresponding '.map' file. */

    /* Strict Type-Checking Options */
    "noImplicitAny": false,                 /* Raise error on expressions and declarations with an implied 'any' type. */
    "strictNullChecks": true,              /* Enable strict null checks. */
    "strictFunctionTypes": true,           /* Enable strict checking of function types. */
    "strictBindCallApply": true,           /* Enable strict 'bind', 'call', and 'apply' methods on functions. */
    "strictPropertyInitialization": true,  /* Enable strict checking of property initialization in classes. */
    "noImplicitThis": true,                /* Raise error on 'this' expressions with an implied 'any' type. */
    "alwaysStrict": true,                  /* Parse in strict mode and emit "use strict" for each source file. */

    /* Additional Checks */
    "noUnusedLocals": true,                /* Report errors on unused locals. */
    "noUnusedParameters": true,            /* Report errors on unused parameters. */
    "noImplicitReturns": true,             /* Report error when not all code paths in function return a value. */
    "noFallthroughCasesInSwitch": true    /* Report errors for fallthrough cases in switch statement. */
  }
}