typescript issues

[selfagency]

sorry to say this has come up again

tsconfig

{
  "include": ["api/**/*"],
  "exclude": ["node_modules", "**/*.spec.ts"],
  "compilerOptions": {
    "target": "ES2020",
    "module": "Node16",
    "rootDir": "./api",
    "moduleResolution": "Node16",
    "types": [
      "node",
      "polka"
    ],
    "resolveJsonModule": true,
    "allowJs": true,
    "sourceMap": true,
    "outDir": "./dist",
    "importHelpers": true,
    "allowSyntheticDefaultImports": true,
    "esModuleInterop": true,
    "forceConsistentCasingInFileNames": true,
    "strict": true,
    "noImplicitAny": false,
    "skipLibCheck": true
  }
}

result

❯ ts-node-esm api/index.ts
/Users/daniel/Library/pnpm/global/5/.pnpm/[email protected]_@[email protected][email protected]/node_modules/ts-node/src/index.ts:859
    return new TSError(diagnosticText, diagnosticCodes, diagnostics);
           ^
TSError: ⨯ Unable to compile TypeScript:
api/index.ts:18:5 - error TS2349: This expression is not callable.
  Type 'typeof import("/Users/daniel/Developer/places-api/node_modules/.pnpm/[email protected]/node_modules/helmet/index")' has no call signatures.

18     helmet({
       ~~~~~~

    at createTSError (/Users/daniel/Library/pnpm/global/5/.pnpm/[email protected]_@[email protected][email protected]/node_modules/ts-node/src/index.ts:859:12)
    at reportTSError (/Users/daniel/Library/pnpm/global/5/.pnpm/[email protected]_@[email protected][email protected]/node_modules/ts-node/src/index.ts:863:19)
    at getOutput (/Users/daniel/Library/pnpm/global/5/.pnpm/[email protected]_@[email protected][email protected]/node_modules/ts-node/src/index.ts:1077:36)
    at Object.compile (/Users/daniel/Library/pnpm/global/5/.pnpm/[email protected]_@[email protected][email protected]/node_modules/ts-node/src/index.ts:1433:41)
    at transformSource (/Users/daniel/Library/pnpm/global/5/.pnpm/[email protected]_@[email protected][email protected]/node_modules/ts-node/src/esm.ts:400:37)
    at /Users/daniel/Library/pnpm/global/5/.pnpm/[email protected]_@[email protected][email protected]/node_modules/ts-node/src/esm.ts:278:53
    at async addShortCircuitFlag (/Users/daniel/Library/pnpm/global/5/.pnpm/[email protected]_@[email protected][email protected]/node_modules/ts-node/src/esm.ts:409:15)
    at async nextLoad (node:internal/modules/esm/loader:163:22)
    at async ESMLoader.load (node:internal/modules/esm/loader:603:20)
    at async ESMLoader.moduleProvider (node:internal/modules/esm/loader:457:11) {
  diagnosticCodes: [ 2349 ]
}

[EvanHahn]

How are you importing Helmet? Could you show me a code snippet that can reproduce this problem?

[selfagency]

import { City, Country, State } from 'country-state-city';
import helmet from 'helmet';
import polka from 'polka';
import bearerToken from 'polka-bearer-token';

const app = polka();
const port = process.env.PORT || 3000;

app
  .use((req, res, next) => {
    res.setHeader('Content-Type', 'application/json');
    res.setHeader('Access-Control-Allow-Origin', '*');
    res.setHeader('Access-Control-Allow-Methods', 'GET, OPTIONS');
    res.setHeader('Access-Control-Allow-Headers', 'Content-Type, Authorization');
    next();
  })
  .use(
    helmet({
      crossOriginResourcePolicy: false,
    })
  )
  .use(bearerToken())
  .use((req, res, next) => {
    const token = (req as typeof req & { token: string }).token.replace('Bearer ', '');
    if (token !== process.env.TOKEN) {
      res.statusCode = 401;
      res.end(JSON.stringify({ message: 'Unauthorized', status: 401 }));
    }
    next();
  })
  .get('/countries', (req, res) => {
    res.end(JSON.stringify(Country.getAllCountries()));
  })
  .get('/countries/:id', (req, res) => {
    res.end(JSON.stringify(Country.getCountryByCode(req.params.id)));
  })
  .get('/states', (req, res) => {
    res.end(JSON.stringify(State.getStatesOfCountry(req.query.country as string)));
  })
  .get('/states/:id', (req, res) => {
    res.end(JSON.stringify(State.getStateByCode(req.params.id)));
  })
  .get('/cities', (req, res) => {
    res.end(JSON.stringify(City.getCitiesOfState(req.query.country as string, req.query.state as string)));
  })
  .get('*', (req, res) => {
    res.statusCode = 404;
    res.end(JSON.stringify({ message: 'Not Found', status: 404 }));
  });

app.listen(port, () => {
  console.log(`Started on ${port}`);
});

[EvanHahn]

I couldn't reproduce this in a reduced sample app. Here's what I have:

package.json:

{
  "private": true,
  "scripts": {
    "typecheck": "tsc --noEmit"
  },
  "dependencies": {
    "helmet": "^7.1.0"
  },
  "devDependencies": {
    "typescript": "^5.6.2"
  }
}

tsconfig.json (modified from yours):

{
  "include": ["app.ts"],
  "compilerOptions": {
    "target": "ES2020",
    "module": "Node16",
    "moduleResolution": "Node16",
    "types": [],
    "resolveJsonModule": true,
    "allowJs": true,
    "sourceMap": true,
    "importHelpers": true,
    "allowSyntheticDefaultImports": true,
    "esModuleInterop": true,
    "forceConsistentCasingInFileNames": true,
    "strict": true,
    "noImplicitAny": false,
    "skipLibCheck": true
  }
}

app.ts (simplified from yours):

import helmet from "helmet";

console.log(
  helmet({
    crossOriginResourcePolicy: false,
  }),
);

What versions are you using? Are any of your dependencies outdated? What about your version of Node.js?

[marc-wittwer]

@EvanHahn I made a reproducible example: https://codesandbox.io/p/devbox/r8t9gx
Run yarn start in the terminal at the bottom to see the error.

The sandbox is using node v20.9.

src/index.ts(7,9): error TS2349: This expression is not callable.
  Type 'typeof import("/node_modules/helmet/index")' has no call signatures.

A potential fix could be to export helmet additionally as a named export.

// index.ts of helmet package
- const helmet: Helmet = Object.assign(
+ export const helmet: Helmet = Object.assign(
  function helmet(options: Readonly<HelmetOptions> = {}) {

More context on how another package has solved a similar issue with module resolution "node16". postcss/postcss#1815

[EvanHahn]

@marc-wittwer Thanks. I'm able to reproduce the issue you're seeing and I'll try to fix it soon.

[fdiazcobos]

Same issue here

[EvanHahn]

I don't know why this is happening, but it seems to be a ts-node issue and not a Helmet issue. (Might be wrong, though!)

On @marc-wittwer's repo, when I run npx tsc --noEmit, it exits with no problems. But when I run ts-node, it gives the error you're seeing.

I don't know why that is. Does anybody have any ideas? Does the problem persist if you switch to another tool like tsx?