用齐博cms建网站,个人网站名称怎么取容易备案,建网站盈利的几种方式,网站的空间与域名1. 基本概念
1.1 什么是 Context
Context 提供了一种在组件树中共享数据的方式#xff0c;而不必通过 props 显式地逐层传递。它主要用于共享那些对于组件树中许多组件来说是全局的数据。
1.2 基本用法
// 1. 创建 Context
const ThemeContext React.createC…1. 基本概念
1.1 什么是 Context
Context 提供了一种在组件树中共享数据的方式而不必通过 props 显式地逐层传递。它主要用于共享那些对于组件树中许多组件来说是全局的数据。
1.2 基本用法
// 1. 创建 Context
const ThemeContext React.createContext(light);// 2. 提供 Context
function App() {return (ThemeContext.Provider valuedarkToolbar //ThemeContext.Provider);
}// 3. 消费 Context
function Toolbar() {return (divThemedButton //div);
}function ThemedButton() {const theme React.useContext(ThemeContext);return button className{theme}Themed Button/button;
}2. Context API 详解
2.1 创建 Context
// 创建 Context 并设置默认值
const UserContext React.createContext({name: Guest,isAdmin: false
});// 导出 Context 供其他组件使用
export default UserContext;2.2 Provider 组件
function App() {const [user, setUser] useState({name: John,isAdmin: true});return (UserContext.Provider value{user}div classNameappMainContent /Sidebar //div/UserContext.Provider);
}2.3 消费 Context
使用 useContext Hook推荐
function UserProfile() {const user React.useContext(UserContext);return (divh2User Profile/h2pName: {user.name}/ppRole: {user.isAdmin ? Admin : User}/p/div);
}使用 Consumer 组件
function UserRole() {return (UserContext.Consumer{user (spanRole: {user.isAdmin ? Admin : User}/span)}/UserContext.Consumer);
}3. 高级用法
3.1 多个 Context 组合
const ThemeContext React.createContext(light);
const UserContext React.createContext({ name: Guest });function App() {return (ThemeContext.Provider valuedarkUserContext.Provider value{{ name: John }}Layout //UserContext.Provider/ThemeContext.Provider);
}function Layout() {const theme React.useContext(ThemeContext);const user React.useContext(UserContext);return (div className{theme}headerWelcome, {user.name}/headermainContent/main/div);
}3.2 动态 Context
const ThemeContext React.createContext({theme: light,toggleTheme: () {}
});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);
}function ThemeToggleButton() {const { theme, toggleTheme } React.useContext(ThemeContext);return (button onClick{toggleTheme}Current theme: {theme}/button);
}3.3 Context 与 TypeScript
// 定义 Context 类型
interface UserContextType {name: string;isAdmin: boolean;updateUser: (name: string) void;
}const UserContext React.createContextUserContextType | undefined(undefined);// 创建自定义 Hook
function useUser() {const context React.useContext(UserContext);if (context undefined) {throw new Error(useUser must be used within a UserProvider);}return context;
}// Provider 组件
function UserProvider({ children }: { children: React.ReactNode }) {const [name, setName] useState(Guest);const [isAdmin] useState(false);const updateUser (newName: string) {setName(newName);};return (UserContext.Provider value{{ name, isAdmin, updateUser }}{children}/UserContext.Provider);
}4. 最佳实践
4.1 创建自定义 Hook
// 创建自定义 Hook 封装 Context 逻辑
function useTheme() {const context React.useContext(ThemeContext);if (context undefined) {throw new Error(useTheme must be used within a ThemeProvider);}return context;
}// 使用自定义 Hook
function ThemedButton() {const { theme, toggleTheme } useTheme();return (button onClick{toggleTheme} className{theme}Toggle Theme/button);
}4.2 分离 Context 逻辑
// contexts/theme.js
export const ThemeContext React.createContext({theme: light,toggleTheme: () {}
});export function ThemeProvider({ children }) {const [theme, setTheme] useState(light);const value {theme,toggleTheme: () setTheme(t t light ? dark : light)};return (ThemeContext.Provider value{value}{children}/ThemeContext.Provider);
}export function useTheme() {const context React.useContext(ThemeContext);if (context undefined) {throw new Error(useTheme must be used within a ThemeProvider);}return context;
}4.3 性能优化
// 使用 memo 避免不必要的重渲染
const UserInfo React.memo(function UserInfo() {const { name } useUser();return divUser: {name}/div;
});// 分离状态避免不相关的更新
function AppProvider({ children }) {return (ThemeProviderUserProviderSettingsProvider{children}/SettingsProvider/UserProvider/ThemeProvider);
}5. 常见问题和解决方案
5.1 避免重渲染
// 使用 useMemo 优化 Context value
function ThemeProvider({ children }) {const [theme, setTheme] useState(light);const value useMemo(() ({theme,toggleTheme: () setTheme(t t light ? dark : light)}), [theme]);return (ThemeContext.Provider value{value}{children}/ThemeContext.Provider);
}5.2 处理嵌套 Context
// 创建组合 Provider
function AppProviders({ children }) {return (AuthProviderThemeProviderUserProvider{children}/UserProvider/ThemeProvider/AuthProvider);
}// 使用组合 Provider
function App() {return (AppProvidersMainApp //AppProviders);
}6. 总结
6.1 使用场景
主题切换用户认证状态语言偏好全局配置路由状态共享
6.2 最佳实践建议
适度使用 Context创建专门的 Provider 组件使用自定义 Hook 封装 Context 逻辑注意性能优化合理组织 Context 结构
