Cannot use import statement outside a module in TypeScript

Cannot use import statement outside a module in TypeScript #

To solve the error "Cannot use import statement outside a module" in TypeScript, set the module option to commonjs in your tsconfig.json file and make sure to compile your TypeScript files (e.g. with ts-node), and not to run them directly with node.

First, make sure the module option is set to commonjs in your tsconfig.json file.

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{
  "compilerOptions": {
    "target": "es6",
    "module": "commonjs",
    "esModuleInterop": true,
    // ... your other options
  }
}

The module option sets the module system for the program.

The esModuleInterop option is set to false by default, which causes it to treat CommonJS modules similar to ES6 modules. This causes some issues. Setting esModuleInterop to true fixes these issues.

Another common cause of the "Cannot use import statement outside a module" error in TypeScript is trying to run a TypeScript file directly with node, e.g. node src/index.ts. This doesn't work, because we first have to transpile the file to JavaScript before we run it with node.

The same is the case if you have incorrectly configured your TypeScript project that uses babel or ts-node.

If your project uses ts-node, you can try to add an override in your tsconfig.json, that sets module to commonjs.

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{
  "ts-node": {
    // these options are overrides used only by ts-node
    "compilerOptions": {
      "module": "commonjs"
    }
  },
  "compilerOptions": {
    // ... your options
  },
}

Take a look at your build folder, which you've set via the outDir option in your tsconfig.json file. Your config could be wrong and you could still be producing TypeScript files in your build directory.

If none of the suggestions above work, take a look at a working config for a TypeScript project that uses ts-node.

This is my tsconfig.json file.

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{
  "compilerOptions": {
    "skipLibCheck": true,
    "target": "es6",
    "module": "commonjs",
    "moduleResolution": "node",
    "allowJs": true,
    "resolveJsonModule": true,
    "esModuleInterop": true,
    "outDir": "./build",
    "rootDir": "src",
  },
  "include": ["src/**/*"],
  "exclude": ["node_modules"]
}

Make sure the include array points to a directory that contains all of the necessary files for your project.

This is my package.json file.

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{
  "name": "example",
  "version": "1.0.0",
  "main": "build/index.js",
  "scripts": {
    "build": "rimraf ./build && tsc",
    "dev": "nodemon",
    "start": "npm run build && node build/index.js",
  },
  "devDependencies": {
    "@types/node": "^17.0.21",
    "nodemon": "^2.0.15",
    "rimraf": "^3.0.0",
    "ts-node": "^10.4.0",
    "typescript": "^4.6.2"
  }
}

And here is the nodemon.json configuration file, which is located in the same directory.

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{
  "watch": ["src"],
  "ext": ".ts,.js",
  "ignore": [],
  "exec": "ts-node --files ./src/index.ts"
}

The ts-node package will transpile your code to JavaScript and run it with node.

Your build files will be in the build directory. Note that your build directory should not contain any TypeScript files, it should only contain JavaScript files.

If your build directory contains TypeScript files, you have a configuration error in your project.