@eslint/v9-to-v10-linter-api
Migrate removed Linter/ESLint constructor options and stricter rule config schema for ESLint v10.
Overview
ESLint v10 removes the configType option, the useFlatConfig option on loadESLint, several Linter instance methods, and tightens the schema for three built-in rules.
What This Codemod Does
Transform 1 — Remove configType from new Linter()
configType: 'flat' is the only supported mode in v10 and no longer needs to be specified. configType: 'eslintrc' is removed with no equivalent — a TODO comment is inserted.
Transform 2 — Remove useFlatConfig from loadESLint()
Transform 3 — Remove deprecated flag values from new ESLint({ flags: [...] })
Transform 4 — Deprecated Linter instance methods → TODO
defineParser(), defineRule(), defineRules(), and getRules() are removed with no direct replacement. Register rules and parsers via the flat config instead.
Transform 5 — func-names stricter schema (remove extra 4th element)
Transform 6 — no-invalid-regexp deduplicate allowConstructorFlags
Transform 7 — radix deprecated string options
The "always" and "as-needed" string options of the radix rule are deprecated in ESLint v10. The rule now always enforces providing a radix argument. "always" is stripped (it is now the sole behavior). "as-needed" is flagged with a TODO because removing it changes the rule's behavior.
Transform 8 — Remove LintMessage.nodeType
LintMessage.nodeType was removed in ESLint v10. Two patterns are handled:
Object property pairs — nodeType: <value> is removed from object literals (common in test assertions):
Member expression accesses — .nodeType in formatters and custom tooling is flagged with a TODO (the surrounding expression must be removed manually):
Usage
After running
Search for TODO comments added by this codemod:
| TODO comment | Action required |
|---|---|
configType "eslintrc" is removed | Rewrite 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() or Linter.getRules() was removed with no equivalent |
LintMessage.nodeType was removed | Remove the surrounding expression that reads message.nodeType |
Limitations
message.nodeTypemember expression accesses are flagged with a TODO but the surrounding expression must be removed manually — the codemod cannot determine what to replace the access with.- Fixer non-string argument validation is not automatable — check manually if you call
fixer.insertTextBefore(node, nonString). loadESLint({ useFlatConfig: true/false, ...otherOptions })is not transformed when extra options are present alongsideuseFlatConfig— removeuseFlatConfigmanually in those cases.new Linter({ configType: 'eslintrc', ...otherOptions })is not flagged with a TODO when additional options are present — add the TODO comment manually.func-namesoptions with nested objects (e.g.{ generators: { mode: 'strict' } }) are not transformed — the regex only matches flat (non-nested) options objects.radixrule with"always"is only stripped when it is the sole option in the array (e.g.['error', 'always']); forms with additional elements are left untouched.