@eslint/v9-to-v10
Migrate ESLint projects from v9 to v10 in a single command. This recipe runs all four v9-to-v10 codemods in sequence.
Usage
What This Recipe Does
This recipe combines the following four codemods into one workflow:
| Codemod | What it handles |
|---|---|
@eslint/v9-to-v10-config | Remove legacy env vars (ESLINT_USE_FLAT_CONFIG) and deprecated CLI flags from shell scripts, package.json scripts, and CI/CD YAML |
@eslint/v9-to-v10-custom-rules | Migrate deprecated context methods and SourceCode methods in custom rule implementations |
@eslint/v9-to-v10-ruletester | Remove properties from RuleTester test cases that ESLint v10 now rejects |
@eslint/v9-to-v10-linter-api | Fix removed Linter/ESLint constructor options, deprecated instance methods, and stricter built-in rule schemas |
Steps (in order)
| # | Step | Transform |
|---|---|---|
| 1 | Remove legacy flags (JS/TS) | ESLINT_USE_FLAT_CONFIG, ESLINT_FLAGS values, --no-eslintrc, --env, --rulesdir, --ignore-path, --resolve-plugins-relative-to from child_process calls |
| 2 | Remove legacy flags (JSON) | Same removals in package.json scripts values |
| 3 | Remove legacy flags (YAML) | Same removals in CI run: steps |
| 4 | Replace context methods | context.getFilename() → context.filename, getCwd() → cwd, etc.; parserOptions → languageOptions.parserOptions |
| 5 | Replace SourceCode methods | getTokenOrCommentBefore/After() → getTokenBefore/After({ includeComments: true }); isSpaceBetweenTokens() → isSpaceBetween() |
| 6 | Clean up valid test cases | Remove errors and output from valid cases in ruleTester.run() |
| 7 | Clean up invalid test cases | Remove type from error objects in invalid cases in ruleTester.run() |
| 8 | Fix Linter constructor | Remove configType, useFlatConfig; strip deprecated flag values; flag deprecated methods |
| 9 | Fix rule options | func-names 4th element, no-invalid-regexp duplicate flags, radix deprecated string options |
| 10 | Fix LintMessage | Remove nodeType property from LintMessage objects; flag .nodeType member accesses |
After Running
Search for TODO comments added by this recipe and address them manually:
| TODO comment | Action required |
|---|---|
configType "eslintrc" is removed | Rewrite the integration to use flat config (eslint.config.js) |
defineParser() removed in ESLint v10 | Register parsers in eslint.config.js languageOptions.parser |
defineRule() removed in ESLint v10 | Register rules in eslint.config.js plugins |
defineRules() removed in ESLint v10 | Register rules in eslint.config.js plugins |
getRules() removed in ESLint v10 | Use ESLint.getRulesMetaForResults() instead |
LintMessage.nodeType was removed | Remove the surrounding expression that reads .nodeType |
context.parserPath removed in ESLint v10 | Use context.languageOptions.parser (object, not path string) |
getJSDocComment removed in ESLint v10 | Use sourceCode.getCommentsBefore(node) with a third-party JSDoc library |
"as-needed" is removed in ESLint v10 | Remove "as-needed" from the radix config or disable the rule |
Limitations
The following cases require manual attention and are not auto-transformed:
/* eslint-env */comments — not removed; add the corresponding globals toeslint.config.jsusing theglobalspackage- Template strings with interpolations in
execSync/execcalls — skipped; inspect and update manually loadESLint({ useFlatConfig, ...extras })— not transformed when extra options are present alongsideuseFlatConfig- Aliased ESLint imports (
import { Linter as L } from 'eslint') — linter-api transforms are not applied to renamed bindings func-nameswith nested options objects — only flat option objects are matchedradix: ['error', 'always', ...]—'always'is only stripped when it is the sole option in the array