tsconfig.json

{
  "compilerOptions": {
    "target": "es2015",
    "module": "commonjs",
    "lib": ["es2015", "es2016", "es2017", "es2018", "dom"],
    "declaration": true,
    "outDir": "./lib",
    "rootDir": "./src/",
    "strictNullChecks": true,
    "noImplicitThis": true,
    "noUnusedParameters": true,
    "noImplicitReturns": true,
    "alwaysStrict": true,
    "noFallthroughCasesInSwitch": true,
    "baseUrl": "./src/",
    "downlevelIteration": false,
    "strict": true,
    "isolatedModules": true,
    "noUncheckedIndexedAccess": true,
    "esModuleInterop": true
  },
  "exclude": ["site", "**/*.test.ts", "lib"]
}