ESLint v9.17.0 released

Highlights

no-unused-vars Suggestions

The no-unused-vars rule provides suggestions now! When the rule sees code with an unused variable like this:

const a = "Hello";
const b = "World!";
console.log(a);

It will now suggest removing the unused variable declaration:

const a = "Hello";

console.log(a);

Suggestions also work for more complex cases like unused function arguments, destructuring syntax, etc.

function avg(a, b, c) {
    return (a + b) / 2;
}

console.log(avg(12, 13, 25));

after the suggestion is applied becomes:

function avg(a, b) {
    return (a + b) / 2;
}

console.log(avg(12, 13, 25));

and

const [{ status, value, reason }] = await Promise.allSettled([promise1, promise2]);

if (status === "rejected") {
    throw reason;
}

after the suggestion becomes:

const [{ status, reason }] = await Promise.allSettled([promise1, promise2]);

if (status === "rejected") {
    throw reason;
}

no-unused-vars suggestions mark the completion of months of work. We will likely further improve and fine-tune this feature in future updates.

Nullish message.fix Allowed

Previously, if a processor returned a LintMessage with a fix property set to undefined or null, ESLint would crash with an unhelpful error message when trying to apply the autofix. This problem has been fixed in the current release.

Features

• eed91d1 feat: add suggestions to no-unused-vars (#18352) (Tanuj Kanti)

Bug Fixes

• 67d683d fix: fix crash when message.fix is nullish (#19168) (ntnyq)
• c618707 fix: ignore vars with non-identifier references in no-useless-assignment (#19200) (YeonJuan)

Documentation

• 3c22d2a docs: update yoda to Yoda in [yoda](/docs/rules/yoda).md for consistency (#19230) (루밀LuMir)
• e0a2203 docs: add missing backticks to no-sequences (#19233) (루밀LuMir)
• 4cc4881 docs: Update README (GitHub Actions Bot)
• 3db6fdf docs: [no-await-in-loop] expand on benefits and inapplicability (#19211) (Kirk Waiblinger)
• bf2a4f6 docs: add missing backticks to func-style (#19227) (루밀LuMir)
• ba098bd docs: add missing header to prefer-spread (#19224) (루밀LuMir)
• b607ae6 docs: update description of no-param-reassign (#19220) (루밀LuMir)
• 1eb424d docs: add missing backticks to prefer-destructuring (#19223) (루밀LuMir)
• 85998d1 docs: add missing backticks to no-unneeded-ternary (#19222) (루밀LuMir)
• b75b32c docs: add missing backticks to no-new-func (#19219) (루밀LuMir)
• a7700bc docs: add missing backticks to id-length (#19217) (루밀LuMir)
• e2bb429 docs: add missing backticks to [complexity](/docs/rules/complexity).md (#19214) (루밀LuMir)
• 045d716 docs: add missing ) to id-denylist (#19213) (루밀LuMir)
• 7fe4114 docs: Update README (GitHub Actions Bot)
• c743ba6 docs: add CSS language to no-restricted-syntax (#19208) (Milos Djermanovic)
• 1416d70 docs: add missing backticks to eqeqeq (#19207) (루밀LuMir)
• b950c1b docs: add missing backticks to prefer-object-spread (#19206) (루밀LuMir)
• 8a941cb docs: update docs and description of require-unicode-regexp (#19205) (루밀LuMir)
• cbab228 docs: Update README (GitHub Actions Bot)
• f2257ce docs: update comments and description of no-script-url (#19203) (루밀LuMir)
• 365f0f4 docs: add missing backtick to default-case-last (#19202) (루밀LuMir)
• e6b84f5 docs: add missing punctuation in document (#19161) (루밀LuMir)
• c88708e docs: replace quote with backtick in description of for-direction (#19199) (루밀LuMir)
• a76f233 docs: use higher contrast color tokens for code comments (#19187) (Josh Goldberg ✨)
• db19502 docs: Update README (GitHub Actions Bot)

Chores

• cc243c9 chore: upgrade to @eslint/js@9.17.0 (#19242) (Francesco Trotta)
• 84c5787 chore: package.json update for @eslint/js release (Jenkins)
• 4c4f53b chore: add missing backticks to flags.js (#19226) (루밀LuMir)
• 4b3132c chore: update dependency eslint-plugin-expect-type to ^0.6.0 (#19221) (renovate[bot])
• 9bf2204 chore: add type definitions for the eslint-config-eslint package (#19050) (Arya Emami)
• ee8c220 chore: fix incorrect name property in integration-tutorial-code (#19218) (루밀LuMir)
• cca801d chore: Upgrade cross-spawn to 7.0.6 (#19185) (folortin)