Getting Error: "All files must be modules when the '--isolatedModules' flag is provide" in React with TypeScript

Question

I can't seem to get rid of this error. I'am using create-react-app with TypeScript. Any help, appreciated. Thanks.

All files must be modules when the '--isolatedModules' flag is provided.  TS1208

  > 1 | import randomcolor from 'randomcolor';
      | ^
    2 | import React from 'react';
    3 | import tasksData from '../../assets/data/tasksData';
    4 | import { Task } from '../../model/task';

These are my tsconfig files. I created a base file as the original tsconfig file gets overwritten by the react build scripts.

tsconfig.base.json

{
    "compilerOptions": {
        "isolatedModules": false
    }
}

tsconfig.json

{
  "compilerOptions": {
    "target": "es5",
    "lib": [
      "dom",
      "dom.iterable",
      "esnext"
    ],
    "allowJs": true,
    "skipLibCheck": true,
    "esModuleInterop": true,
    "allowSyntheticDefaultImports": true,
    "strict": true,
    "forceConsistentCasingInFileNames": true,
    "module": "esnext",
    "moduleResolution": "node",
    "resolveJsonModule": true,
    "isolatedModules": true,
    "noEmit": true,
    "jsx": "react"
  },
  "include": [
    "src"
  ],
  "exclude": [
    "node_modules"
  ],
  "extends": "./tsconfig.base.json"
}

Answer 1

The problem is that in Typescript by default, every file without importor export is a legacy scrip file.

As such files are not modules they are merged in the global namespace.

To change this behavior

a) add any import or export in the file, eg: export {}

b) set "isolatedModules": false in tsconfig.json

Note: NextJS will reset the value to true in every build, because for NextJS, "isolatedModules": true is a requirement

Answer 2

May get this error with an unused .tsor .tsx file. I had empty .ts file I wasn't using so just had to delete the unused file.

deleted the unused file /example/index.ts