Issue with eslint-config-airbnb-base and optional chaining operator

[kayomarz]

Issue with eslint-config-airbnb-base and optional chaining operator ?. (JavaScript)

// .eslintrc.js
module.exports = {
  env: { es2021: true },
  extends: [ 'airbnb-base' ]
};

const o = {};
const a = o?.a;

For the above code, ESLint reports Parsing error: Unexpected token at the optional chaining operator ?.

ESLint rules for optional chaining should work with parserOption: {ecmaVersion: 2020} or higher and which eslint automatically sets because env: {es2021: true} is used in the config above.

However when airbnb-base is used, an explicit parserOption: ecmaVersion: 12 seems to be required to resolve the above issue as such:

// .eslintrc.js
module.exports = {
  env: { es2021: true },
  extends: [ 'airbnb-base' ],
  parserOptions: { ecmaVersion: 12 }
};

(Note: ecmaVersion: 11 should also work)

The error does not occur without airbnb-base as below:

// .eslintrc.js
module.exports = {
  env: { es2021: true }
};

Although the fix is simply to explicitly state ecmaVersion it can take a while to figure out that the Parsing error: Unexpected token is because of airbnb-base.

When this issue occors, all other lint errors in the file are not reported which means eslint stops working!

For a better developer experience, this issue could be looked into or documented well.

The above issue occurred with:

Local ESLint version: ^8.7.0
Global ESLint version: ^8.7.0
Node version: v14.17.3
npm version: 6.14.13
Operating System: Linux

[ljharb]

Does babel-preset-airbnb transform that yet? If so, then

javascript/packages/eslint-config-airbnb-base/index.js

Line 13 in b4377fb

ecmaVersion: 2018,

can be updated.