Skip to content

Latest commit

 

History

History
224 lines (155 loc) · 11.5 KB

migrate-to-9.0.0.md

File metadata and controls

224 lines (155 loc) · 11.5 KB
Raw
title eleventyNavigation
Migrate to v9.x
key parent title order
migrate to v9
use eslint
Migrate to v9.x
7

ESLint v9.0.0 is a major release of ESLint, and as such, has several breaking changes that you need to be aware of. This guide is intended to walk you through the breaking changes.

The lists below are ordered roughly by the number of users each change is expected to affect, where the first items are expected to affect the most users.

Table of Contents

Breaking changes for users

Breaking changes for plugin developers

Breaking changes for integration developers

Node.js < v18.18, v19 are no longer supported

ESLint is officially dropping support for these versions of Node.js starting with ESLint v9.0.0. ESLint now supports the following versions of Node.js:

  • Node.js v18.18.0 and above
  • Node.js v20.9.0 and above
  • Node.js v21 and above

To address: Make sure you upgrade to at least Node.js v18.18.0 when using ESLint v9.0.0. One important thing to double check is the Node.js version supported by your editor when using ESLint via editor integrations. If you are unable to upgrade, we recommend continuing to use ESLint v8.56.0 until you are able to upgrade Node.js.

Related issue(s): #17595

Removed multiple formatters

ESLint v9.0.0 has removed the following formatters from the core:

Removed Formatter Replacement npm Package
checkstyle eslint-formatter-checkstyle
compact eslint-formatter-compact
jslint-xml eslint-formatter-jslint-xml
junit eslint-formatter-junit
tap eslint-formatter-tap
unix eslint-formatter-unix
visualstudio eslint-formatter-visualstudio

To address: If you are using any of these formatters via the -f command line flag, you'll need to install the respective package for the formatter.

Related issue(s): #17524

Removed require-jsdoc and valid-jsdoc rules

The require-jsdoc and valid-jsdoc rules have been removed in ESLint v9.0.0. These rules were initially deprecated in 2018.

To address: Use the replacement rules in eslint-plugin-jsdoc.

Related issue(s): #15820

eslint:recommended has been updated

Four new rules have been enabled in eslint:recommended:

Additionally, the following rules have been removed from eslint:recommended:

To address: Fix errors or disable these rules.

Related issue(s): #15576, #17446, #17596

Removed multiple context methods

ESLint v9.0.0 removes multiple deprecated methods from the context object and moves them onto the SourceCode object:

Removed on context Replacement(s) on SourceCode
context.getSource() sourceCode.getText()
context.getSourceLines() sourceCode.getLines()
context.getAllComments() sourceCode.getAllComments()
context.getNodeByRangeIndex() sourceCode.getNodeByRangeIndex()
context.getComments() sourceCode.getCommentsBefore(), sourceCode.getCommentsAfter(), sourceCode.getCommentsInside()
context.getCommentsBefore() sourceCode.getCommentsBefore()
context.getCommentsAfter() sourceCode.getCommentsAfter()
context.getCommentsInside() sourceCode.getCommentsInside()
context.getJSDocComment() sourceCode.getJSDocComment()
context.getFirstToken() sourceCode.getFirstToken()
context.getFirstTokens() sourceCode.getFirstTokens()
context.getLastToken() sourceCode.getLastToken()
context.getLastTokens() sourceCode.getLastTokens()
context.getTokenAfter() sourceCode.getTokenAfter()
context.getTokenBefore() sourceCode.getTokenBefore()
context.getTokenByRangeStart() sourceCode.getTokenByRangeStart()
context.getTokens() sourceCode.getTokens()
context.getTokensAfter() sourceCode.getTokensAfter()
context.getTokensBefore() sourceCode.getTokensBefore()
context.getTokensBetween() sourceCode.getTokensBetween()
context.parserServices sourceCode.parserServices

To address: Following the recommendations in the blog post.

Related Issues(s): #16999, #13481

Removed sourceCode.getComments()

ESLint v9.0.0 removes the deprecated sourceCode.getComments() method.

To address: Replace with sourceCode.getCommentsBefore(), sourceCode.getCommentsAfter(), or sourceCode.getCommentsInside().

Related Issues(s): #14744

Function-style rules are no longer supported

ESLint v9.0.0 drops support for function-style rules. Function-style rules are rules created by exporting a function rather than an object with a create() method. This rule format was deprecated in 2016.

To address: Update your rules to the most recent rule format.

The eslint-plugin/prefer-object-rule rule can help enforce the usage of object-style rules and autofix any remaining function-style rules.

Related Issues(s): #14709

meta.schema is required for rules with options

As of ESLint v9.0.0, an error will be thrown if any options are passed to a rule that doesn't specify meta.schema property.

To address:

  • If your rule expects options, set meta.schema property to a JSON Schema format description of the rule’s options. This schema will be used by ESLint to validate configured options and prevent invalid or unexpected inputs to your rule.
  • If your rule doesn't expect any options, there is no action required. This change ensures that end users will not mistakenly configure options for rules that don't expect options.
  • (not recommended) you can also set meta.schema to false to disable this validation, but it is highly recommended to provide a schema if the rule expects options and omit the schema (or set []) if the rule doesn't expect options so that ESLint can ensure that your users' configurations are valid.

The eslint-plugin/require-meta-schema rule can help enforce that rules have schemas when required.

Related Issues(s): #14709

FlatRuleTester is now RuleTester

As announced in our blog post, the temporary FlatRuleTester class has been renamed to RuleTester, while the RuleTester class from v8.x has been removed. Additionally, the FlatRuleTester export from eslint/use-at-your-own-risk has been removed.

To address: Update your rule tests to use the new RuleTester. To do so, here are some of the common changes you'll need to make:

  • Be aware of new defaults for ecmaVersion and sourceType. By default, RuleTester uses the flat config default of ecmaVersion: "latest" and sourceType: "module". This may cause some tests to break if they were expecting the old default of ecmaVersion: 5 and sourceType: "script". If you'd like to use the old default, you'll need to manually specify that in your RuleTester like this:

    // use eslintrc defaults
const ruleTester = new RuleTester({
    languageOptions: {
        ecmaVersion: 5,
        sourceType: "script"
    }
});

  • Change parserOptions to languageOptions. If you're setting ecmaVersion or sourceType on your tests, move those from parserOptions to languageOptions, like this:

    ruleTester.run("my-rule", myRule, {
    valid: [
        {
            code: "foo",
            parserOptions: {
                ecmaVersion: 6
            }
        }
    ]
});

// becomes

ruleTester.run("my-rule", myRule, {
    valid: [
        {
            code: "foo",
            languageOptions: {
                ecmaVersion: 6
            }
        }
    ]
});

  • Translate other config keys. Keys such as env and parser that used to run on the eslintrc config system must be translated into the flat config system. Please refer to the Configuration Migration Guide for details on translating other keys you may be using.

Related Issues(s): #13481

FlatESLint is now ESLint

As announced in our blog post, the temporary FlatESLint class has been renamed to ESLint, while the ESLint class from v8.x has been renamed to LegacyESLint.

To address: If you are currently using the ESLint class, verify that your tests pass using the new ESLint class. Not all of the old options are supported, so you may need to update the arguments passed to the constructor. See the Node.js API Reference for details.

If you still need the v8.x ESLint functionality, use the LegacyESLint class like this:

const { LegacyESLint } = require("eslint/use-at-your-own-risk");

Related Issues(s): #13481