eslint v9 support

[ljharb]

(see also #2478, #2223, #2036, #1834, #1447)

eslint v9 was released on 2024.04.05.

The current plan is, if possible, to release a new semver-minor of both configs, that supports 7 || 8 || 9.

Note that this is different from whether flat config is supported or not by these plugins, and from whether this project will convert to flat config.

The timeframe for eslint v9 support is "not as soon as you would like, but as soon as we can".
Please accept this, and please add no noise to this thread beyond emoji reactions - distractions won't help anyone get the work done any faster.

Please do not file additional issues and do not file pull requests attempting to add support - please, instead, continue to use eslint v8 until such time as our configs support v9.

Peer Dep eslint combined v7, v8, and v9 support released:

• eslint-plugin-import (PR)
  • flat config support (PR)
• eslint-find-rules
• update the base config
• publish the base config, semver-minor
• eslint-plugin-react
  • flat config support
• eslint-plugin-jsx-a11y (PR)
  • flat config support
• eslint-plugin-react-hooks
  • v9 support (PR)
  • flat config support (PR)
• update the main config
• publish the main config, semver-minor

[dgtllion]

I see it will take a bit longer than I expected. Has anyone a workaround while its in progress?

[ljharb]

@dgtllion this is still within the expected timeframe. The workaround is "stick with eslint 8 for now".

[dgtllion]

@dgtllion this is still within the expected timeframe. The workaround is "stick with eslint 8 for now".

My goal is to move to eslint v9. I think your advice is more to stayaround instead of workaround.
May be anyone has another workaround like patching, use another config package or something else (while its in progress)?

[xfournet]

@dgtllion here is an excerpt of what I use to make airbnb works in ESLint 9 : https://gist.github.com/xfournet/ed9f2f02e411b86188bad4aeb9b1bddb

[controversial]

Here’s the workaround I’m using for eslint-config-airbnb on eslint 9, including:

• automatically migrating legacy config to flat config using FlatCompat
• automatically replacing deprecated rules that should be moved to @stylistic/eslint
• (optional) within typescript files, automatically using the @typescript-eslint version of any rules that are available under typescript-eslint

import { FlatCompat } from '@eslint/eslintrc';
import js from '@eslint/js';

import tseslint from 'typescript-eslint';
import stylisticPlugin from '@stylistic/eslint-plugin';


// Load airbnb config as FlatConfig
const compat = new FlatCompat({
  baseDirectory: import.meta.dirname,
  recommendedConfig: js.configs.recommended,
  allConfig: js.configs.all,
});
const airbnbFlat = compat.extends('eslint-config-airbnb');
// Extract list of rules
const baseRuleEntries = airbnbFlat.flatMap((cfg) => (cfg.rules ? Object.entries(cfg.rules) : []));


// 1. Replace deprecated stylistic rules with rules from stylistic plugin
const ruleEntriesWithStylisticVersion = baseRuleEntries
  .map(([rule, setting]) => [rule.split('/').at(-1), setting])
  .filter(([rule]) => rule in stylisticPlugin.rules);
const stylisticPatchedRules = {
  ...Object.fromEntries(baseRuleEntries),
  ...stylisticPlugin.configs['disable-legacy'].rules,
  ...Object.fromEntries(ruleEntriesWithStylisticVersion.map(([rule, setting]) => [`@stylistic/${rule}`, setting])),
};

// 2. For typescript config, replace rules that have a typescript-eslint version
const ruleEntriesWithTsEslintVersion = baseRuleEntries
  .filter(([rule]) => rule in (tseslint.plugin.rules ?? {}));
const typescriptPatchedRules = Object.fromEntries([
  ...ruleEntriesWithTsEslintVersion.map(([rule]) => [rule, 'off']),
  ...ruleEntriesWithTsEslintVersion.map(([rule, setting]) => [`@typescript-eslint/${rule}`, setting]),
]);

export default [
  // Base rules - patched to use stylistic plugin
  {
    plugins: { '@stylistic': stylisticPlugin },
    rules: stylisticPatchedRules,
  },

  // Within typescript files, use the @typescript-eslint version of any rule we can
  {
    files:['**/*.ts', '**/*.tsx', '**/*.d.ts'],
    rules: typescriptPatchedRules,
  },
];

[ljharb]

@dgtllion you can't move to eslint 9 yet while using the airbnb config in a supported fashion. You can choose to be unsupported (using the workaround above, for example), or choose to wait on eslint 8 (which is perfectly reasonable and won't obstruct anything meaningful), or choose to stop using the airbnb config.