在浏览器上/重新加载/或返回页面时如何使主题状态持久化？

debugcn 发表于 Dev

德雷

当用户重新加载，访问新页面或在浏览器上按回鼠标等等时，如何使我的亮/暗主题永久保存为一种状态。...现在非常不一致。

这是我设置主题的index.js。我将其包裹在组件周围。

index.js

import { ThemeProvider, CssBaseline } from "@material-ui/core";
import { createMuiTheme } from "@material-ui/core";

const MyThemeContext = React.createContext({});

export function useMyThemeContext() {
    return useContext(MyThemeContext);
  }
  
function MyThemeProvider(props) {
  const [isDarkMode, setIsDarkMode] = useState(false);

  const theme = useMemo(
    () =>
      createMuiTheme({
        palette: {
          type: isDarkMode ? 'dark' : 'light',
        },
      }),
    [isDarkMode]
  );

  return (
    <ThemeProvider theme={theme}>
      <MyThemeContext.Provider value={{ isDarkMode, setIsDarkMode }}>
        {props.children}
      </MyThemeContext.Provider>
    </ThemeProvider>
  );
}


const routing = (
    <Router>
        <React.StrictMode>
            <MyThemeProvider>
                <CssBaseline />
                    <Header />
                    <Switch>
                        <Route exact path="/" component={App} />
                        <Route path="/register" component={Register} />
                        <Route path="/login" component={Login} />
                        <Route path="/logout" component={Logout} />
                        <Route path="/dash/:slug" component={Bucket} />
                        <Route path="/create" component={CreateBucket}/>
                    </Switch>
                    <Footer />
            </MyThemeProvider>
        </React.StrictMode>
    </Router>
);

ReactDOM.render(routing, document.getElementById('root'));

我使用一个激活主题状态的开关，它位于我的标题中。 header.js

import React from 'react';
import AppBar from '@material-ui/core/AppBar';
import Toolbar from '@material-ui/core/Toolbar';
import Typography from '@material-ui/core/Typography';
import CssBaseline from '@material-ui/core/CssBaseline';
import { makeStyles } from '@material-ui/core/styles';
import { NavLink } from 'react-router-dom';
import Link from '@material-ui/core/Link';
import Button from '@material-ui/core/Button';
import Switch from '@material-ui/core/Switch';
import { useMyThemeContext } from '../index';


const useStyles = makeStyles((theme) => ({
    appBar: {
        borderBottom: `1px solid ${theme.palette.divider}`,
    },
    link: {
        margin: theme.spacing(1, 1.5),
    },
    toolbarTitle: {
        flexGrow: 1,
    },
}));


function Header() {
    const classes = useStyles();

    const {isDarkMode, setIsDarkMode} = useMyThemeContext();

    return (
        <React.Fragment>
            <CssBaseline />
            <AppBar
                position="static"
                color="default"
                elevation={0}
                className={classes.appBar}
            >
                <Toolbar className={classes.toolbar}>
                    <Switch
                        checked={isDarkMode}
                        onChange={() => setIsDarkMode(!isDarkMode)}
                    />
                </Toolbar>
            </AppBar>
        </React.Fragment>
    );
}

export default Header;

如何解决状态不保存的矛盾？感谢您的帮助！

布扎托

您将使用localStorage密钥名将状态保留在内存中。在应用程序重新加载时，您的初始状态将来自存储在中的值localStorage，如果未设置，!!则将确保该值false不是null

同时传递给Provider更新状态并将新值设置为的函数localStorage。这样一来，您无需记住在localStorage消耗消耗的每个位置设置值setIsDarkMode

// if it's not set in localStorage value is null, then !! will set as false
const initialState = !!JSON.parse(localStorage.getItem('theme'))

function MyThemeProvider(props) {
  const [isDarkMode, setIsDarkMode] = useState(initialState);

  // you pass another function where you persist the value to localStorage
  // given your code you may just create a toggle function where you don't need to pass a value. but you can change it to receive an argument
  const toggleDarkMode = () => {
    setIsDarkMode(themeMode => {
      localStorage.setItem('theme', !themeMode)
      return !themeMode
    })
  }

  const theme = useMemo(
    () =>
      createMuiTheme({
        palette: {
          type: isDarkMode ? 'dark' : 'light',
        },
      }),
    [isDarkMode]
  );

  return (
    <ThemeProvider theme={theme}>
      <MyThemeContext.Provider value={{ isDarkMode, toggleDarkMode }}>
        {props.children}
      </MyThemeContext.Provider>
    </ThemeProvider>
  );
}

然后Header您提取toggleDarkMode：

function Header() {
    const classes = useStyles();

    const {isDarkMode, toggleDarkMode} = useMyThemeContext();

    return (
        <React.Fragment>
            <CssBaseline />
            <AppBar
                position="static"
                color="default"
                elevation={0}
                className={classes.appBar}
            >
                <Toolbar className={classes.toolbar}>
                    <Switch
                        checked={isDarkMode}
                        onChange={toggleDarkMode}
                    />
                </Toolbar>
            </AppBar>
        </React.Fragment>
    );
}

export default Header;

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