前端状态管理：别让你的状态变成一团乱麻
前端状态管理：别让你的状态变成一团乱麻
毒舌时刻
这状态管理得跟蜘蛛网似的，谁能理得清？
各位前端同行，咱们今天聊聊前端状态管理。别告诉我你还在使用 setState 管理所有状态，那感觉就像在没有地图的情况下寻宝——能找，但累死你。
为什么你需要状态管理
最近看到一个项目，组件之间传递状态需要经过 5 层，修改一个状态要修改多个地方。我就想问：你是在做状态管理还是在做传递游戏？
反面教材
// 反面教材：混乱的状态管理 function App() { const [user, setUser] = useState(null); const [posts, setPosts] = useState([]); const [comments, setComments] = useState([]); const [loading, setLoading] = useState(true); useEffect(() => { async function fetchData() { setLoading(true); try { const userResponse = await fetch('/api/user'); const userData = await userResponse.json(); setUser(userData); const postsResponse = await fetch('/api/posts'); const postsData = await postsResponse.json(); setPosts(postsData); const commentsResponse = await fetch('/api/comments'); const commentsData = await commentsResponse.json(); setComments(commentsData); } catch (error) { console.error('Error fetching data:', error); } finally { setLoading(false); } } fetchData(); }, []); return ( <div> {loading ? <div>加载中...</div> : ( <div> <UserHeader user={user} /> <PostList posts={posts} comments={comments} /> </div> )} </div> ); } function UserHeader({ user }) { return <h1>Welcome, {user?.name}</h1>; } function PostList({ posts, comments }) { return ( <div> {posts.map(post => ( <div key={post.id}> <h2>{post.title}</h2> <p>{post.content}</p> <CommentList postId={post.id} comments={comments} /> </div> ))} </div> ); } function CommentList({ postId, comments }) { const postComments = comments.filter(comment => comment.postId === postId); return ( <div> {postComments.map(comment => ( <div key={comment.id}>{comment.content}</div> ))} </div> ); } 毒舌点评：这状态管理，就像在玩传球游戏，球传来传去都不知道传到哪里了。
正确姿势
1. Redux Toolkit
// 正确姿势：Redux Toolkit // 1. 安装依赖 // npm install @reduxjs/toolkit react-redux // 2. 创建 store // store/index.js import { configureStore } from '@reduxjs/toolkit'; import userReducer from './slices/userSlice'; import postsReducer from './slices/postsSlice'; import commentsReducer from './slices/commentsSlice'; export const store = configureStore({ reducer: { user: userReducer, posts: postsReducer, comments: commentsReducer, }, }); // 3. 创建 slices // store/slices/userSlice.js import { createSlice, createAsyncThunk } from '@reduxjs/toolkit'; export const fetchUser = createAsyncThunk('user/fetchUser', async () => { const response = await fetch('/api/user'); return response.json(); }); const userSlice = createSlice({ name: 'user', initialState: { data: null, loading: false, error: null, }, reducers: {}, extraReducers: (builder) => { builder .addCase(fetchUser.pending, (state) => { state.loading = true; state.error = null; }) .addCase(fetchUser.fulfilled, (state, action) => { state.loading = false; state.data = action.payload; }) .addCase(fetchUser.rejected, (state, action) => { state.loading = false; state.error = action.error.message; }); }, }); export default userSlice.reducer; // 4. 使用 store // index.js import React from 'react'; import ReactDOM from 'react-dom/client'; import App from './App'; import { Provider } from 'react-redux'; import { store } from './store'; ReactDOM.createRoot(document.getElementById('root')).render( <Provider store={store}> <App /> </Provider> ); // 5. 使用状态 // App.jsx import React, { useEffect } from 'react'; import { useDispatch, useSelector } from 'react-redux'; import { fetchUser } from './store/slices/userSlice'; import { fetchPosts } from './store/slices/postsSlice'; import { fetchComments } from './store/slices/commentsSlice'; import UserHeader from './components/UserHeader'; import PostList from './components/PostList'; function App() { const dispatch = useDispatch(); const { loading } = useSelector((state) => state.user); useEffect(() => { dispatch(fetchUser()); dispatch(fetchPosts()); dispatch(fetchComments()); }, [dispatch]); return ( <div> {loading ? <div>加载中...</div> : ( <div> <UserHeader /> <PostList /> </div> )} </div> ); } // components/UserHeader.jsx import React from 'react'; import { useSelector } from 'react-redux'; function UserHeader() { const user = useSelector((state) => state.user.data); return <h1>Welcome, {user?.name}</h1>; } export default UserHeader; // components/PostList.jsx import React from 'react'; import { useSelector } from 'react-redux'; import CommentList from './CommentList'; function PostList() { const posts = useSelector((state) => state.posts.data); return ( <div> {posts.map(post => ( <div key={post.id}> <h2>{post.title}</h2> <p>{post.content}</p> <CommentList postId={post.id} /> </div> ))} </div> ); } export default PostList; // components/CommentList.jsx import React from 'react'; import { useSelector } from 'react-redux'; function CommentList({ postId }) { const comments = useSelector((state) => state.comments.data.filter(comment => comment.postId === postId) ); return ( <div> {comments.map(comment => ( <div key={comment.id}>{comment.content}</div> ))} </div> ); } export default CommentList; 2. Zustand
// 正确姿势：Zustand // 1. 安装依赖 // npm install zustand // 2. 创建 store // store/index.js import { create } from 'zustand'; import { persist } from 'zustand/middleware'; const useStore = create( persist( (set, get) => ({ user: null, posts: [], comments: [], loading: false, error: null, fetchUser: async () => { set({ loading: true, error: null }); try { const response = await fetch('/api/user'); const data = await response.json(); set({ user: data, loading: false }); } catch (error) { set({ error: error.message, loading: false }); } }, fetchPosts: async () => { set({ loading: true, error: null }); try { const response = await fetch('/api/posts'); const data = await response.json(); set({ posts: data, loading: false }); } catch (error) { set({ error: error.message, loading: false }); } }, fetchComments: async () => { set({ loading: true, error: null }); try { const response = await fetch('/api/comments'); const data = await response.json(); set({ comments: data, loading: false }); } catch (error) { set({ error: error.message, loading: false }); } }, }), { name: 'app-storage', } ) ); export default useStore; // 3. 使用 store // App.jsx import React, { useEffect } from 'react'; import useStore from './store'; import UserHeader from './components/UserHeader'; import PostList from './components/PostList'; function App() { const { loading, fetchUser, fetchPosts, fetchComments } = useStore(); useEffect(() => { fetchUser(); fetchPosts(); fetchComments(); }, [fetchUser, fetchPosts, fetchComments]); return ( <div> {loading ? <div>加载中...</div> : ( <div> <UserHeader /> <PostList /> </div> )} </div> ); } // components/UserHeader.jsx import React from 'react'; import useStore from '../store'; function UserHeader() { const user = useStore((state) => state.user); return <h1>Welcome, {user?.name}</h1>; } export default UserHeader; // components/PostList.jsx import React from 'react'; import useStore from '../store'; import CommentList from './CommentList'; function PostList() { const posts = useStore((state) => state.posts); return ( <div> {posts.map(post => ( <div key={post.id}> <h2>{post.title}</h2> <p>{post.content}</p> <CommentList postId={post.id} /> </div> ))} </div> ); } export default PostList; // components/CommentList.jsx import React from 'react'; import useStore from '../store'; function CommentList({ postId }) { const comments = useStore((state) => state.comments.filter(comment => comment.postId === postId) ); return ( <div> {comments.map(comment => ( <div key={comment.id}>{comment.content}</div> ))} </div> ); } export default CommentList; 3. Jotai
// 正确姿势：Jotai // 1. 安装依赖 // npm install jotai // 2. 创建 atoms // store/atoms.js import { atom, useAtom, useAtomValue, useSetAtom } from 'jotai'; import { atomWithStorage } from 'jotai/utils'; // 状态 atoms const userAtom = atomWithStorage('user', null); const postsAtom = atomWithStorage('posts', []); const commentsAtom = atomWithStorage('comments', []); const loadingAtom = atom(false); const errorAtom = atom(null); // 动作 atoms const fetchUserAtom = atom( null, async (_, set) => { set(loadingAtom, true); set(errorAtom, null); try { const response = await fetch('/api/user'); const data = await response.json(); set(userAtom, data); } catch (error) { set(errorAtom, error.message); } finally { set(loadingAtom, false); } } ); const fetchPostsAtom = atom( null, async (_, set) => { set(loadingAtom, true); set(errorAtom, null); try { const response = await fetch('/api/posts'); const data = await response.json(); set(postsAtom, data); } catch (error) { set(errorAtom, error.message); } finally { set(loadingAtom, false); } } ); const fetchCommentsAtom = atom( null, async (_, set) => { set(loadingAtom, true); set(errorAtom, null); try { const response = await fetch('/api/comments'); const data = await response.json(); set(commentsAtom, data); } catch (error) { set(errorAtom, error.message); } finally { set(loadingAtom, false); } } ); export { userAtom, postsAtom, commentsAtom, loadingAtom, errorAtom, fetchUserAtom, fetchPostsAtom, fetchCommentsAtom }; // 3. 使用 atoms // App.jsx import React, { useEffect } from 'react'; import { useAtomValue, useSetAtom } from 'jotai'; import { loadingAtom, fetchUserAtom, fetchPostsAtom, fetchCommentsAtom } from './store/atoms'; import UserHeader from './components/UserHeader'; import PostList from './components/PostList'; function App() { const loading = useAtomValue(loadingAtom); const fetchUser = useSetAtom(fetchUserAtom); const fetchPosts = useSetAtom(fetchPostsAtom); const fetchComments = useSetAtom(fetchCommentsAtom); useEffect(() => { fetchUser(); fetchPosts(); fetchComments(); }, [fetchUser, fetchPosts, fetchComments]); return ( <div> {loading ? <div>加载中...</div> : ( <div> <UserHeader /> <PostList /> </div> )} </div> ); } // components/UserHeader.jsx import React from 'react'; import { useAtomValue } from 'jotai'; import { userAtom } from '../store/atoms'; function UserHeader() { const user = useAtomValue(userAtom); return <h1>Welcome, {user?.name}</h1>; } export default UserHeader; // components/PostList.jsx import React from 'react'; import { useAtomValue } from 'jotai'; import { postsAtom } from '../store/atoms'; import CommentList from './CommentList'; function PostList() { const posts = useAtomValue(postsAtom); return ( <div> {posts.map(post => ( <div key={post.id}> <h2>{post.title}</h2> <p>{post.content}</p> <CommentList postId={post.id} /> </div> ))} </div> ); } export default PostList; // components/CommentList.jsx import React from 'react'; import { useAtomValue } from 'jotai'; import { commentsAtom } from '../store/atoms'; function CommentList({ postId }) { const comments = useAtomValue(commentsAtom); const postComments = comments.filter(comment => comment.postId === postId); return ( <div> {postComments.map(comment => ( <div key={comment.id}>{comment.content}</div> ))} </div> ); } export default CommentList; 毒舌点评：这才叫前端状态管理，集中管理状态，组件之间共享状态，再也不用担心状态传递的问题了。
