tsconfig.json

{
  "compilerOptions": {
    "target": "es2018",
    "lib": ["es2018", "dom"] /* Specify library files to be included in the compilation. */,
    "allowJs": true /* Allow javascript files to be compiled. */,
    "checkJs": true /* Report errors in .js files. */,
    "declaration": true,
    "outDir": "./dist",
    "rootDir": "./",
    "emitDeclarationOnly": true,
    "strict": true,
    "noImplicitAny": false,
    "moduleResolution": "node" /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */,
    "baseUrl": "./" /* Base directory to resolve non-absolute module names. */,
    "paths": {
      "y-codemirror": ["src/index.js"]
    },
    "maxNodeModuleJsDepth": 0,
    "allowSyntheticDefaultImports": true
  },
  "include": ["src/index.js", "./demo/codemirror.js"]
}