本文最后更新于 2024-10-17，文章内容可能已经过时。

React 进阶阶段学习计划

目标

掌握自定义Hooks的创建和使用。
深入理解上下文（Context）和Redux的高级用法。
学会服务端渲染（SSR）。
深入探讨性能优化技巧。

学习内容

自定义Hooks

创建和使用自定义Hooks

自定义Hooks：用于提取组件逻辑，使代码更加模块化和复用。

示例：

// useFetch.js
import { useState, useEffect } from 'react';

function useFetch(url) {
  const [data, setData] = useState(null);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState(null);

  useEffect(() => {
    async function fetchData() {
      try {
        const response = await fetch(url);
        const json = await response.json();
        setData(json);
      } catch (err) {
        setError(err);
      } finally {
        setLoading(false);
      }
    }

    fetchData();
  }, [url]);

  return { data, loading, error };
}

export default useFetch;

// App.js
import React from 'react';
import useFetch from './useFetch';

function App() {
  const { data, loading, error } = useFetch('https://jsonplaceholder.typicode.com/posts');

  if (loading) return <div>Loading...</div>;
  if (error) return <div>Error: {error.message}</div>;

  return (
    <div>
      <h1>Data from API</h1>
      <ul>
        {data.map(item => (
          <li key={item.id}>{item.title}</li>
        ))}
      </ul>
    </div>
  );
}

export default App;

上下文（Context）和Redux的高级用法

上下文（Context）的高级用法

Context Consumer：用于在函数组件中消费Context。

示例：

// ThemeContext.js
import React, { createContext, useContext, useState } from 'react';

const ThemeContext = createContext();

// 提供者组件
function ThemeProvider({ children }) {
  const [theme, setTheme] = useState('light');

  const toggleTheme = () => {
    setTheme((prevTheme) => (prevTheme === 'light' ? 'dark' : 'light'));
  };

  return (
    <ThemeContext.Provider value={{ theme, toggleTheme }}>
      {children}
    </ThemeContext.Provider>
  );
}

// 消费者组件
function ThemedButton() {
  const { theme, toggleTheme } = useContext(ThemeContext);

  return (
    <button onClick={toggleTheme} style={{ background: theme === 'light' ? '#fff' : '#333', color: theme === 'light' ? '#000' : '#fff' }}>
      Toggle Theme
    </button>
  );
}

// App.js
import React from 'react';
import ThemeProvider from './ThemeProvider';
import ThemedButton from './ThemedButton';

function App() {
  return (
    <ThemeProvider>
      <ThemedButton />
    </ThemeProvider>
  );
}

export default App;

Redux的高级用法

Redux Toolkit：简化Redux的开发流程。

安装：

npm install @reduxjs/toolkit react-redux

示例：

// store.js
import { configureStore, createSlice } from '@reduxjs/toolkit';

const counterSlice = createSlice({
  name: 'counter',
  initialState: { value: 0 },
  reducers: {
    increment: (state) => {
      state.value += 1;
    },
    decrement: (state) => {
      state.value -= 1;
    },
  },
});

const store = configureStore({
  reducer: {
    counter: counterSlice.reducer,
  },
});

export const { increment, decrement } = counterSlice.actions;
export default store;

// App.js
import React from 'react';
import { useSelector, useDispatch } from 'react-redux';
import { increment, decrement } from './store';
import { Provider } from 'react-redux';
import store from './store';

function Counter() {
  const count = useSelector((state) => state.counter.value);
  const dispatch = useDispatch();

  return (
    <div>
      <p>Count: {count}</p>
      <button onClick={() => dispatch(increment())}>Increment</button>
      <button onClick={() => dispatch(decrement())}>Decrement</button>
    </div>
  );
}

function App() {
  return (
    <Provider store={store}>
      <Counter />
    </Provider>
  );
}

export default App;

服务端渲染（SSR）

Next.js

Next.js：一个流行的React框架，支持服务端渲染。

安装：

npx create-next-app@latest my-app
cd my-app
npm run dev

示例：

// pages/index.js
import { useState } from 'react';

export default function Home() {
  const [count, setCount] = useState(0);

  return (
    <div>
      <h1>Welcome to Next.js!</h1>
      <p>Count: {count}</p>
      <button onClick={() => setCount(count + 1)}>Increment</button>
    </div>
  );
}

// pages/api/hello.js
export default function handler(req, res) {
  res.status(200).json({ name: 'John Doe' });
}

性能优化的深入探讨

使用React Profiler

React Profiler：用于分析组件的渲染性能。

启用Profiler：

import React, { Profiler } from 'react';

function onRender(id, phase, actualDuration, baseDuration, startTime, commitTime) {
  console.log({ id, phase, actualDuration, baseDuration, startTime, commitTime });
}

function App() {
  return (
    <Profiler id="App" onRender={onRender}>
      <div>
        <h1>React Profiler Example</h1>
        {/* 其他组件 */}
      </div>
    </Profiler>
  );
}

export default App;

使用React.memo和PureComponent

React.memo：用于优化函数组件的性能。
PureComponent：用于优化类组件的性能。

示例：

// MyComponent.js
import React, { PureComponent } from 'react';

class MyComponent extends PureComponent {
  render() {
    return <div>{this.props.value}</div>;
  }
}

export default MyComponent;

// MyFunctionComponent.js
import React from 'react';

const MyFunctionComponent = React.memo(({ value }) => {
  return <div>{value}</div>;
});

export default MyFunctionComponent;

实践项目

社交媒体应用

创建项目：

npx create-next-app@latest social-media-app
cd social-media-app
npm run dev

创建组件：

PostList.js：显示帖子列表

import React, { useState, useEffect } from 'react';
import axios from 'axios';

function PostList() {
  const [posts, setPosts] = useState([]);

  useEffect(() => {
    axios.get('https://jsonplaceholder.typicode.com/posts')
      .then(response => {
        setPosts(response.data);
      })
      .catch(error => {
        console.error('Error fetching posts:', error);
      });
  }, []);

  return (
    <div className="post-list">
      {posts.map(post => (
        <div key={post.id} className="post">
          <h3>{post.title}</h3>
          <p>{post.body}</p>
        </div>
      ))}
    </div>
  );
}

export default PostList;

App.js：主组件

import React from 'react';
import PostList from '../components/PostList';

function Home() {
  return (
    <div className="container">
      <h1>Social Media App</h1>
      <PostList />
    </div>
  );
}

export default Home;

博客管理系统

创建项目：

npx create-react-app blog-management --template typescript
cd blog-management
npm start

安装axios：
```
npm install axios
```

创建组件：

PostForm.tsx：添加和编辑帖子的表单

import React, { useState } from 'react';
import axios from 'axios';

interface Post {
  id?: number;
  title: string;
  content: string;
}

interface PostFormProps {
  initialPost?: Post;
  onSubmit: (post: Post) => void;
}

const PostForm: React.FC<PostFormProps> = ({ initialPost, onSubmit }) => {
  const [post, setPost] = useState<Post>({
    id: initialPost?.id,
    title: initialPost?.title || '',
    content: initialPost?.content || '',
  });

  const handleSubmit = async (e: React.FormEvent) => {
    e.preventDefault();
    onSubmit(post);
    setPost({ title: '', content: '' });
  };

  return (
    <form onSubmit={handleSubmit}>
      <input
        type="text"
        value={post.title}
        onChange={(e) => setPost({ ...post, title: e.target.value })}
        placeholder="Title"
      />
      <textarea
        value={post.content}
        onChange={(e) => setPost({ ...post, content: e.target.value })}
        placeholder="Content"
      />
      <button type="submit">Submit</button>
    </form>
  );
};

export default PostForm;

PostList.tsx：显示帖子列表

import React, { useState, useEffect } from 'react';
import axios from 'axios';
import PostForm from './PostForm';

interface Post {
  id: number;
  title: string;
  content: string;
}

const PostList: React.FC = () => {
  const [posts, setPosts] = useState<Post[]>([]);
  const [editingPost, setEditingPost] = useState<Post | null>(null);

  useEffect(() => {
    axios.get<Post[]>('https://jsonplaceholder.typicode.com/posts')
      .then(response => {
        setPosts(response.data.slice(0, 10));
      })
      .catch(error => {
        console.error('Error fetching posts:', error);
      });
  }, []);

  const handleEdit = (post: Post) => {
    setEditingPost(post);
  };

  const handleDelete = (postId: number) => {
    setPosts(posts.filter(post => post.id !== postId));
  };

  const handleSave = (post: Post) => {
    if (post.id) {
      setPosts(posts.map(p => (p.id === post.id ? post : p)));
    } else {
      setPosts([...posts, post]);
    }
    setEditingPost(null);
  };

  return (
    <div className="post-list">
      {editingPost ? (
        <PostForm initialPost={editingPost} onSubmit={handleSave} />
      ) : (
        <PostForm onSubmit={handleSave} />
      )}
      <ul>
        {posts.map(post => (
          <li key={post.id}>
            <h3>{post.title}</h3>
            <p>{post.content}</p>
            <button onClick={() => handleEdit(post)}>Edit</button>
            <button onClick={() => handleDelete(post.id)}>Delete</button>
          </li>
        ))}
      </ul>
    </div>
  );
};

export default PostList;

App.tsx：主组件

import React from 'react';
import PostList from './components/PostList';

const App: React.FC = () => {
  return (
    <div className="App">
      <h1>Blog Management System</h1>
      <PostList />
    </div>
  );
};

export default App;

建议

定期回顾：每周花时间回顾本周所学内容，确保知识点牢固掌握。
参与社区：加入React相关的论坛、Slack群组或Discord服务器，与其他开发者交流心得。
阅读源码：尝试阅读一些复杂的React库的源码，提高代码理解和分析能力。

希望这个学习计划能够帮助你系统地学习React进阶技能，并通过实践项目巩固所学知识。祝你学习顺利！


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