Parsing error: 'import' and 'export' may appear only with 'sourceType: module'

[johanbook]

This seems like a really cool eslint config! I gave it a try on a typescript project with eslint config

{
  "extends": ["hardcore", "hardcore/fp", "hardcore/node"],
  "overrides": [
    {
      "files": ["*.js"],
      "extends": ["hardcore/ts-for-js"],
      "parserOptions": { "project": "./tsconfig.json" }
    }
  ]
}

and get the error

/home/pong/utils/src/cookies/cookies.ts
  3:1  error  Parsing error: 'import' and 'export' may appear only with 'sourceType: module'

I tried with a ts config of {} as suggested in readme.

I am using E6 syntax and want to use the import/export syntax. Do you know what has gone wrong here?

[EvgenyOrekhov]

The default value for sourceType is script (see https://eslint.org/docs/user-guide/configuring#specifying-parser-options). If you want to use ES6 modules, you have to set "sourceType": "module" in parserOptions.

Regarding TypeScript, I have not tried using eslint-config-hardcore with TypeScript, and I have no idea whether it would work or not. And the hardcore/ts-for-js config is meant for linting JavaScript projects, not TypeScript projects (it contains only a small subset of rules, specific to JavaScript).

[EvgenyOrekhov]

Please let me know if "sourceType": "module" fixed your issue.

[EvgenyOrekhov]

BTW, I can see that Node.js 14 was promoted to LTS two days ago, which means now we should be able to use ES6 modules both on client side and on server side. I guess I should set "sourceType": "module" as default in eslint-config-hardcore then. And also discourage the use of commonjs. Created #164.

[johanbook]

In which cases would you want to use eslint-typscript for regular javascript?

I tried adding some variations of parserOptions but seems to get

> eslint `src/**/*.ts`


Oops! Something went wrong! :(

ESLint: 7.12.1

No files matching the pattern "/home/pong//utils" were found.
Please check for typing mistakes in the pattern.

Bit unfamiliar to Eslint, do you know why this might be?

[EvgenyOrekhov]

In which cases would you want to use eslint-typscript for regular javascript?

• when you use new ES features, like class properties or optional chaining, and want to run additional checks on those
• when you want to run additional type-aware checks

Here are some useful typescript-eslint rules that work with JavaScript (they all are included in hardcore/ts-for-js):

• lines-between-class-members
• require-await
• return-await
• await-thenable
• no-floating-promises
• no-misused-promises
• promise-function-async
• no-throw-literal
• unbound-method
• prefer-optional-chain
• naming-convention - I really like this one, I was able to enforce boolean naming with it (boolean names have to begin with a prefix, like is/has/should)
• and a few other rules

---

No files matching the pattern "/home/pong//utils" were found.

Looks like you are facing a known issue with eslint-plugin-import and its import/no-unused-modules rule, see import-js/eslint-plugin-import#1645. I guess you should just disable this rule.

Let me know if that helps.

[EvgenyOrekhov]

BTW, I noticed you have "files": ["*.js"] in your overrides section. If you want to lint *.ts files, you should change it to "files": ["*.ts", "*.js"].

[johanbook]

Aha, I see. With the config

{
  "extends": ["hardcore", "hardcore/fp", "hardcore/node"],
  "parserOptions": {
    "ecmaVersion": 6,
    "sourceType": "script"
  },
  "overrides": [
    {
      "files": ["*.ts"],
      "extends": ["hardcore/ts-for-js"],
      "parserOptions": { "project": "./tsconfig.json" },
      "rules": {"import/no-unused-modules": "off"}
    }
  ]
}

> eslint 'src/**/*.ts'


Oops! Something went wrong! :(

ESLint: 7.12.1

TypeError: Cannot read property 'node' of undefined
Occurred while linting /home/pong/test-hardcore/src/cookies/index.ts:1
    at /home/pong/test-hardcore/node_modules/eslint-plugin-import/lib/rules/no-namespace.js:28:26
    at Array.find (<anonymous>)
    at ImportNamespaceSpecifier (/home/book/@book/utils-hardcore/node_modules/eslint-plugin-import/lib/rules/no-namespace.js:27:50)
    at /home/book/@book/utils-hardcore/node_modules/eslint/lib/linter/safe-emitter.js:45:58
    at Array.forEach (<anonymous>)
    at Object.emit (/home/book/@book/utils-hardcore/node_modules/eslint/lib/linter/safe-emitter.js:45:38)
    at NodeEventGenerator.applySelector (/home/book/@book/utils-hardcore/node_modules/eslint/lib/linter/node-event-generator.js:254:26)
    at NodeEventGenerator.applySelectors (/home/book/@book/utils-hardcore/node_modules/eslint/lib/linter/node-event-generator.js:283:22)
    at NodeEventGenerator.enterNode (/home/book/@book/utils-hardcore/node_modules/eslint/lib/linter/node-event-generator.js:297:14)
    at CodePathAnalyzer.enterNode (/home/book/@book/utils-hardcore/node_modules/eslint/lib/linter/code-path-analysis/code-path-analyzer.js:711:23)
npm ERR! code ELIFECYCLE

But then I'll look for another config for typescript ☺️

[EvgenyOrekhov]

TypeError: Cannot read property 'node' of undefined

That's unfortunate :( I can see in the stack trace that it's related to the import/no-namespace rule. Feel free to report it to eslint-plugin-import's repo.