tsconfig.json

{
  "compilerOptions": {
    "module": "commonjs",
    "moduleResolution": "node",
    "lib": ["es2017"],
    "jsx": "react", // uses typescript to transpile jsx to js
    "target": "es5", // specify ECMAScript target version
    "allowJs": true, // allows a partial TypeScript and JavaScript codebase
    "declaration": true,
    "checkJs": false, // checks types in .js files (https://github.com/microsoft/TypeScript/wiki/Type-Checking-JavaScript-Files)
    "allowSyntheticDefaultImports": true,
    "resolveJsonModule": true,
    "skipLibCheck": true,
    "outDir": "dist",
    "downlevelIteration": true,
    "noEmit": false,
    "noImplicitAny": false,
    "esModuleInterop": true,
    "sourceMap": true
  },
  "include": [
    "src/ol/**/*.js"
  ]
}