Import and export declarations are not supported yet (in TS)

The problem

When trying to use import or export statements in TypeScript (*.ts) files eslint complains:

Import and export declarations are not supported yet.
eslint(node/no-unsupported-features/es-syntax)

Solution

Add following rule config to your eslint settings:

//.eslintrc.js
module.exports = {
  ...
  rules: {
    "node/no-unsupported-features/es-syntax": [
      "error",
      { ignores: ["modules"] },
    ],
  },
  ...
}

Notes

My full eslint configuration for reference:

//.eslintrc.js
module.exports = {
  root: true,
  parser: "@typescript-eslint/parser",
  parserOptions: {
    ecmaVersion: 2018,
    sourceType: "module",
  },
  plugins: ["node", "unicorn", "prettier", "@typescript-eslint"],
  extends: [
    "eslint:recommended",
    "plugin:node/recommended",
    "plugin:unicorn/recommended",
    "plugin:prettier/recommended",
    "plugin:@typescript-eslint/recommended",
    "prettier",
  ],
  env: {
    node: true,
  },
  rules: {
    "no-console": "error",
    "unicorn/no-array-reduce": "off",
    "prettier/prettier": "error",
    "@typescript-eslint/no-var-requires": "off",
    "node/no-unsupported-features/es-syntax": [
      "error",
      { ignores: ["modules"] },
    ],
  },
  settings: {
    node: {
      tryExtensions: [".js", ".json", ".node", ".ts"],
    },
  },
};

This only works when I have following settings in package.json:

//package.json
{ 
  ...
  "type": "commonjs",
  ...
}

References

• StackOverflow post
• GitHub issue

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Comments

[Sergei Novikov]

Hello! I want you to ask about unicorn plugin. What for we need to use it?

[Michal Bryxí]

Hi Sergei unicorn is popular eslint plugin that adds some extra formatting rules. You don't need it at all. I attached the full config only because I think setting up all the extends / plugins is very confusing and this should give the reader ability to have copy&paste solution. If you know what you're doing, adding the extra rules option is a way to go.

[Sergei Novikov]

Michal thanks! I google it but wasn't sure. Actually i'm starting to use airbnb's rules in my project and have never heard about unicorn before. And I'm wondering if anyone has compared them?

[Michal Bryxí]

Not sure tbh. Quick look at the Airbnb one it seems that:

• It requires more involvement (have to use additional packages)
• They have some rules that do care about old browsers
• Are the rules auto-fixable? Maybe another article would be good for that.