tsconfig.json

{ // TypeScript configuration file: provides options to the TypeScript 
  // compiler (tsc) and makes VSCode recognize this folder as a TS project,
  // enabling the VSCode build tasks "tsc: build" and "tsc: watch".
  "compilerOptions": {
    "lib": ["es2015", "dom"],
    "target": "es5", // Compatible with older browsers
    "module": "commonjs", // Compatible with both Node.js and browser
    "moduleResolution": "node", // Tell tsc to look in node_modules for modules
    "sourceMap": true, // Creates *.js.map files
    "strict": true, // Strict types, eg. prohibits `var x=0; x=null`
    "alwaysStrict": true // Enable JavaScript's "use strict" mode
  },
  "include": [
    "**/*.ts"
  ],
  "exclude": [
    "node_modules",
    "**/*.spec.ts"
  ]
}