tsconfig.json

{
  "compilerOptions": {
    "target": "es5",                          /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017','ES2018' or 'ESNEXT'. */
    "module": "commonjs",                     /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', or 'ESNext'. */
    "lib": ["dom","es2015"],                             /* Specify library files to be included in the compilation. */
    "declaration": true,                   /* Generates corresponding '.d.ts' file. */
    "outDir": "./dist",                        /* Redirect output structure to the directory. */
    "strict": true,                           /* Enable all strict type-checking options. */
    "noImplicitAny": false,                 /* Raise error on expressions and declarations with an implied 'any' type. */
    "strictPropertyInitialization": false,  /* Enable strict checking of property initialization in classes. */
    "moduleResolution": "node",            /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
    "esModuleInterop": true,                   /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */
    "experimentalDecorators": true,        /* Enables experimental support for ES7 decorators. */
  },
  "include": [
    "./src",
    "./tests/**.ts"
  ]
}