build: use typescript-eslint@v6 internally

.eslintrc.cjs

@@ -1,8 +1,17 @@
 module.exports = {
- extends: 'react-app',
+ extends: [
+ 'react-app',
+ 'plugin:@typescript-eslint/recommended-type-checked',
+ 'plugin:@typescript-eslint/stylistic-type-checked'
+ ],
 
  parser: '@typescript-eslint/parser',
 
+ parserOptions: {
+ project: true,
+ tsconfigRootDir: __dirname
+ },
+
  plugins: ['@typescript-eslint'],
 
  settings: {
@@ -21,7 +30,8 @@ module.exports = {
  rules: {
  'jsx-a11y/href-no-hash': 'off',
  'no-unused-vars': 'off',
- '@typescript-eslint/no-unused-expressions': 'off',
+
+ // These off/not-configured-the-way-we-want lint rules we like & opt into
  '@typescript-eslint/no-unused-vars': [
  'error',
  {
@@ -31,6 +41,33 @@ module.exports = {
  argsIgnorePattern: '^_',
  varsIgnorePattern: '^_'
  }
- ]
+ ],
+ '@typescript-eslint/restrict-template-expressions': [
+ 'error',
+ {
+ allowNever: true
+ }
+ ],
+
+ // Todo: investigate whether we'd like these on
+ '@typescript-eslint/ban-ts-comment': 'off',
+ '@typescript-eslint/ban-types': 'off',
+ '@typescript-eslint/consistent-indexed-object-style': 'off',
+ '@typescript-eslint/consistent-type-definitions': 'off',
+ '@typescript-eslint/no-confusing-void-expression': 'off',
+ '@typescript-eslint/no-empty-function': 'off',
+ '@typescript-eslint/no-floating-promises': 'off',
+ '@typescript-eslint/no-unsafe-argument': 'off',
+ '@typescript-eslint/no-unsafe-assignment': 'off',
+ '@typescript-eslint/no-unsafe-call': 'off',
+ '@typescript-eslint/no-unsafe-member-access': 'off',
+ '@typescript-eslint/no-unsafe-return': 'off',
+ '@typescript-eslint/prefer-function-type': 'off',
+ '@typescript-eslint/sort-type-constituents': 'off',
+ '@typescript-eslint/unbound-method': 'off',
+ 'prefer-rest-params': 'off',
+
+ // These lint rules don't make sense for us but are enabled in the preset configs
+ '@typescript-eslint/no-unused-expressions': 'off'
  }
 }

package.json

@@ -59,8 +59,8 @@
  "devDependencies": {
  "@babel/core": "^7.19.0",
  "@types/node": "^18.7.16",
- "@typescript-eslint/eslint-plugin": "^5.36.2",
- "@typescript-eslint/parser": "^5.36.2",
+ "@typescript-eslint/eslint-plugin": "6.0.0-alpha.158",
+ "@typescript-eslint/parser": "6.0.0-alpha.158",
  "cross-env": "^7.0.3",
  "esbuild-extra": "^0.1.3",
  "eslint": "^8.23.0",
@@ -78,5 +78,9 @@
  "typescript": "^4.8.3",
  "vitest": "^0.27.2"
  },
+ "resolutions": {
+ "@typescript-eslint/eslint-plugin": "6.0.0-alpha.158",
+ "@typescript-eslint/parser": "6.0.0-alpha.158"
+ },
  "sideEffects": false
 }

src/applyMiddleware.ts

@@ -64,7 +64,7 @@ export default function applyMiddleware(
 
  const middlewareAPI: MiddlewareAPI = {
  getState: store.getState,
- dispatch: (action, ...args) => dispatch(action, ...args)
+ dispatch: (action, ...args: unknown[]) => dispatch(action, ...args)
  }
  const chain = middlewares.map(middleware => middleware(middlewareAPI))
  dispatch = compose<typeof dispatch>(...chain)(store.dispatch)

src/combineReducers.ts

@@ -125,9 +125,7 @@ export default function combineReducers(reducers: {
 }) {
  const reducerKeys = Object.keys(reducers)
  const finalReducers: { [key: string]: Reducer<any, any, any> } = {}
- for (let i = 0; i < reducerKeys.length; i++) {
- const key = reducerKeys[i]
-
+ for (const key of reducerKeys) {
  if (process.env.NODE_ENV !== 'production') {
  if (typeof reducers[key] === 'undefined') {
  warning(`No reducer provided for key "${key}"`)
@@ -176,13 +174,12 @@ export default function combineReducers(reducers: {
 
  let hasChanged = false
  const nextState: StateFromReducersMapObject<typeof reducers> = {}
- for (let i = 0; i < finalReducerKeys.length; i++) {
- const key = finalReducerKeys[i]
+ for (const key of finalReducerKeys) {
  const reducer = finalReducers[key]
  const previousStateForKey = state[key]
  const nextStateForKey = reducer(previousStateForKey, action)
  if (typeof nextStateForKey === 'undefined') {
- const actionType = action && action.type
+ const actionType = action?.type
  throw new Error(
  `When called with an action of type ${
  actionType ? `"${String(actionType)}"` : '(unknown type)'

test/combineReducers.spec.ts

@@ -15,7 +15,7 @@ describe('Utils', () => {
  type PushAction = { type: 'push'; value: unknown }
 
  const reducer = combineReducers({
- counter: (state: number = 0, action: IncrementAction) =>
+ counter: (state = 0, action: IncrementAction) =>
  action.type === 'increment' ? state + 1 : state,
  stack: (state: any[] = [], action: PushAction) =>
  action.type === 'push' ? [...state, action.value] : state
@@ -64,8 +64,8 @@ describe('Utils', () => {
 
  it('throws an error if a reducer returns undefined handling an action', () => {
  const reducer = combineReducers({
- counter(state: number = 0, action: Action) {
- switch (action && action.type) {
+ counter(state = 0, action: Action) {
+ switch (action?.type) {
  case 'increment':
  return state + 1
  case 'decrement':

test/createStore.spec.ts

@@ -431,7 +431,7 @@ describe('createStore', () => {
  const store = createStore(reducers.todos)
 
  let resolve: (value: unknown) => void = () => {}
- let promise = new Promise(_resolve => {
+ const promise = new Promise(_resolve => {
  resolve = _resolve
  })
  store.subscribe(() => {
@@ -451,7 +451,7 @@ describe('createStore', () => {
  it('does not leak private listeners array', async () => {
  const store = createStore(reducers.todos)
  let resolve: (value: unknown) => void = () => {}
- let promise = new Promise(_resolve => {
+ const promise = new Promise(_resolve => {
  resolve = _resolve
  })
 

test/typescript/actions.ts

@@ -23,7 +23,7 @@ namespace FreeShapeAction {
  text: 'test'
  }
 
- const text: string = action['text']
+ const text: string = action.text
 }
 
 namespace StringLiteralTypeAction {

test/typescript/store.ts

@@ -101,10 +101,10 @@ const storeWithCombineReducerAndBadPreloadedState = createStore(
 )
 
 const nestedCombinedReducer = combineReducers({
- a: (state: string = 'a') => state,
+ a: (state = 'a') => state,
  b: combineReducers({
- c: (state: string = 'c') => state,
- d: (state: string = 'd') => state
+ c: (state = 'c') => state,
+ d: (state = 'd') => state
  }),
  e: (state: BrandedString = brandedString) => state
 })
@@ -116,8 +116,8 @@ const storeWithNestedCombineReducer = createStore(nestedCombinedReducer, {
 })
 
 const simpleCombinedReducer = combineReducers({
- c: (state: string = 'c') => state,
- d: (state: string = 'd') => state
+ c: (state = 'c') => state,
+ d: (state = 'd') => state
 })
 
 // @ts-expect-error