add react hooks for accessing redux store state and dispatching redux actions

Author: MrWolfZ

package.json

@@ -29,7 +29,7 @@
     "build": "npm run build:commonjs && npm run build:es && npm run build:umd && npm run build:umd:min",
     "clean": "rimraf lib dist es coverage",
     "format": "prettier --write \"{src,test}/**/*.{js,ts}\" index.d.ts \"docs/**/*.md\"",
-    "lint": "eslint src test/utils test/components",
+    "lint": "eslint src test/utils test/components test/hooks",
     "prepare": "npm run clean && npm run build",
     "pretest": "npm run lint",
     "test": "jest",

src/alternate-renderers.js

@@ -3,9 +3,26 @@ import connectAdvanced from './components/connectAdvanced'
 import { ReactReduxContext } from './components/Context'
 import connect from './connect/connect'
 
+import { useActions } from './hooks/useActions'
+import { useDispatch } from './hooks/useDispatch'
+import { useReduxContext } from './hooks/useReduxContext'
+import { useSelector } from './hooks/useSelector'
+import { useStore } from './hooks/useStore'
+
 import { getBatch } from './utils/batch'
 
 // For other renderers besides ReactDOM and React Native, use the default noop batch function
 const batch = getBatch()
 
-export { Provider, connectAdvanced, ReactReduxContext, connect, batch }
+export {
+  Provider,
+  connectAdvanced,
+  ReactReduxContext,
+  connect,
+  batch,
+  useActions,
+  useDispatch,
+  useReduxContext,
+  useSelector,
+  useStore
+}

src/hooks/useActions.js

@@ -0,0 +1,74 @@
+import { bindActionCreators } from 'redux'
+import invariant from 'invariant'
+import { useDispatch } from './useDispatch'
+import { useMemo } from 'react'
+
+/**
+ * A hook to bind action creators to the redux store's `dispatch` function
+ * similar to how redux's `bindActionCreators` works.
+ * 
+ * Supports passing a single action creator, an array/tuple of action
+ * creators, or an object of action creators.
+ * 
+ * Any arguments passed to the created callbacks are passed through to
+ * the your functions.
+ * 
+ * This hook takes a dependencies array as an optional second argument,
+ * which when passed ensures referential stability of the created callbacks.
+ * 
+ * @param {Function|Function[]|Object.<string, Function>} actions the action creators to bind
+ * @param {any[]} deps (optional) dependencies array to control referential stability
+ * 
+ * @returns {Function|Function[]|Object.<string, Function>} callback(s) bound to store's `dispatch` function
+ *
+ * Usage:
+ *
+```jsx
+import React from 'react'
+import { useActions } from 'react-redux'
+
+const increaseCounter = ({ amount }) => ({
+  type: 'increase-counter',
+  amount,
+})
+
+export const CounterComponent = ({ value }) => {
+  // supports passing an object of action creators
+  const { increaseCounterByOne, increaseCounterByTwo } = useActions({
+    increaseCounterByOne: () => increaseCounter(1),
+    increaseCounterByTwo: () => increaseCounter(2),
+  }, [])
+
+  // supports passing an array/tuple of action creators
+  const [increaseCounterByThree, increaseCounterByFour] = useActions([
+    () => increaseCounter(3),
+    () => increaseCounter(4),
+  ], [])
+
+  // supports passing a single action creator
+  const increaseCounterBy5 = useActions(() => increaseCounter(5), [])
+
+  // passes through any arguments to the callback
+  const increaseCounterByX = useActions(x => increaseCounter(x), [])
+
+  return (
+    <div>
+      <span>{value}</span>
+      <button onClick={increaseCounterByOne}>Increase counter by 1</button>
+    </div>
+  )
+}
+```
+ */
+export function useActions(actions, deps) {
+  invariant(actions, `You must pass actions to useActions`)
+
+  const dispatch = useDispatch()
+  return useMemo(() => {
+    if (Array.isArray(actions)) {
+      return actions.map(a => bindActionCreators(a, dispatch))
+    }
+
+    return bindActionCreators(actions, dispatch)
+  }, deps)
+}

src/hooks/useDispatch.js

@@ -0,0 +1,31 @@
+import { useStore } from './useStore'
+
+/**
+ * A hook to access the redux `dispatch` function. Note that in most cases where you
+ * might want to use this hook it is recommended to use `useActions` instead to bind
+ * action creators to the `dispatch` function.
+ * 
+ * @returns {any} redux store's `dispatch` function
+ *
+ * Usage:
+ *
+```jsx
+import React, { useCallback } from 'react'
+import { useReduxDispatch } from 'react-redux'
+
+export const CounterComponent = ({ value }) => {
+  const dispatch = useDispatch()
+  const increaseCounter = useCallback(() => dispatch({ type: 'increase-counter' }), [])
+  return (
+    <div>
+      <span>{value}</span>
+      <button onClick={increaseCounter}>Increase counter</button>
+    </div>
+  )
+}
+```
+ */
+export function useDispatch() {
+  const store = useStore()
+  return store.dispatch
+}

src/hooks/useReduxContext.js

@@ -0,0 +1,32 @@
+import { useContext } from 'react'
+import invariant from 'invariant'
+import { ReactReduxContext } from '../components/Context'
+
+/**
+ * A hook to access the value of the `ReactReduxContext`. This is a low-level
+ * hook that you should usually not need to call directly.
+ * 
+ * @returns {any} the value of the `ReactReduxContext`
+ *
+ * Usage:
+ *
+```jsx
+import React from 'react'
+import { useReduxContext } from 'react-redux'
+
+export const CounterComponent = ({ value }) => {
+  const { store } = useReduxContext()
+  return <div>{store.getState()}</div>
+}
+```
+ */
+export function useReduxContext() {
+  const contextValue = useContext(ReactReduxContext)
+
+  invariant(
+    contextValue,
+    'could not find react-redux context value; please ensure the component is wrapped in a <Provider>'
+  )
+
+  return contextValue
+}

src/hooks/useSelector.js

@@ -0,0 +1,87 @@
+import { useReducer, useRef, useEffect, useMemo, useLayoutEffect } from 'react'
+import invariant from 'invariant'
+import { useReduxContext } from './useReduxContext'
+import shallowEqual from '../utils/shallowEqual'
+import Subscription from '../utils/Subscription'
+
+// React currently throws a warning when using useLayoutEffect on the server.
+// To get around it, we can conditionally useEffect on the server (no-op) and
+// useLayoutEffect in the browser. We need useLayoutEffect to ensure the store
+// subscription callback always has the selector from the latest render commit
+// available, otherwise a store update may happen between render and the effect,
+// which may cause missed updates; we also must ensure the store subscription
+// is created synchronously, otherwise a store update may occur before the
+// subscription is created and an inconsistent state may be observed
+const useIsomorphicLayoutEffect =
+  typeof window !== 'undefined' ? useLayoutEffect : useEffect
+
+/**
+ * A hook to access the redux store's state. This hook takes a selector function
+ * as an argument. The selector is called with the store state.
+ * 
+ * @param {Function} selector the selector function
+ * 
+ * @returns {any} the selected state
+ *
+ * Usage:
+ *
+```jsx
+import React from 'react'
+import { useSelector } from 'react-redux'
+
+export const CounterComponent = () => {
+  const counter = useSelector(state => state.counter)
+  return <div>{counter}</div>
+}
+```
+ */
+export function useSelector(selector) {
+  invariant(selector, `You must pass a selector to useSelectors`)
+
+  const { store, subscription: contextSub } = useReduxContext()
+  const [, forceRender] = useReducer(s => s + 1, 0)
+
+  const subscription = useMemo(() => new Subscription(store, contextSub), [
+    store,
+    contextSub
+  ])
+
+  const latestSelector = useRef(selector)
+  const selectedState = selector(store.getState())
+  const latestSelectedState = useRef(selectedState)
+
+  useIsomorphicLayoutEffect(() => {
+    latestSelector.current = selector
+    latestSelectedState.current = selectedState
+  })
+
+  useIsomorphicLayoutEffect(() => {
+    function checkForUpdates() {
+      try {
+        const newSelectedState = latestSelector.current(store.getState())
+
+        if (shallowEqual(newSelectedState, latestSelectedState.current)) {
+          return
+        }
+
+        latestSelectedState.current = newSelectedState
+      } catch {
+        // we ignore all errors here, since when the component
+        // is re-rendered, the selectors are called again, and
+        // will throw again, if neither props nor store state
+        // changed
+      }
+
+      forceRender({})
+    }
+
+    subscription.onStateChange = checkForUpdates
+    subscription.trySubscribe()
+
+    checkForUpdates()
+
+    return () => subscription.tryUnsubscribe()
+  }, [store, subscription])
+
+  return selectedState
+}

src/hooks/useStore.js

@@ -0,0 +1,23 @@
+import { useReduxContext } from './useReduxContext'
+
+/**
+ * A hook to access the redux store.
+ * 
+ * @returns {any} the redux store
+ *
+ * Usage:
+ *
+```jsx
+import React from 'react'
+import { useStore } from 'react-redux'
+
+export const CounterComponent = ({ value }) => {
+  const store = useStore()
+  return <div>{store.getState()}</div>
+}
+```
+ */
+export function useStore() {
+  const { store } = useReduxContext()
+  return store
+}

src/index.js

@@ -3,9 +3,26 @@ import connectAdvanced from './components/connectAdvanced'
 import { ReactReduxContext } from './components/Context'
 import connect from './connect/connect'
 
+import { useActions } from './hooks/useActions'
+import { useDispatch } from './hooks/useDispatch'
+import { useReduxContext } from './hooks/useReduxContext'
+import { useSelector } from './hooks/useSelector'
+import { useStore } from './hooks/useStore'
+
 import { setBatch } from './utils/batch'
 import { unstable_batchedUpdates as batch } from './utils/reactBatchedUpdates'
 
 setBatch(batch)
 
-export { Provider, connectAdvanced, ReactReduxContext, connect, batch }
+export {
+  Provider,
+  connectAdvanced,
+  ReactReduxContext,
+  connect,
+  batch,
+  useActions,
+  useDispatch,
+  useReduxContext,
+  useSelector,
+  useStore
+}