Question

我正在尝试使用材料ui中的代码，并收到此错误：

Invalid hook call. Hooks can only be called inside of the body of a function component. 
This could happen for one of the following reasons:
1. You might have mismatching versions of React and the renderer (such as React DOM)
2. You might be breaking the Rules of Hooks
3. You might have more than one copy of React in the same app

如果我不使用类，我不确定是什么原因引起的（因为我知道不能在类中使用react钩子）。我想知道这是否与ReactDOM有关？

这是我正在使用的唯一代码：

======= index.js =======

import React from 'react';
import ReactDOM from 'react-dom';
import App from './Pages/HomePage.jsx';

ReactDOM.render(<App />, document.getElementById('root'));

======== HomePage.js =======

import React, { useState } from 'react';
import AB from '../Components/AppBar';

export default function HP() {
  const [buttonClicked, setButtonClicked] = useState(false);

  if (buttonClicked === false ) 
      return (
          <Button color="info" onClick={() => setButtonClicked(true)}>Get Started</Button>
      )
  if (buttonClicked) return (<AB/>)
};

======== AppBar.js =======

import React from 'react';
import AppBar from '@material-ui/core/AppBar';
import Toolbar from '@material-ui/core/Toolbar';
import IconButton from '@material-ui/core/IconButton';
import Typography from '@material-ui/core/Typography';
import InputBase from '@material-ui/core/InputBase';
import { fade, makeStyles } from '@material-ui/core/styles';
import MenuIcon from '@material-ui/icons/Menu';
import SearchIcon from '@material-ui/icons/Search';

const useStyles = makeStyles(theme => ({
  root: {
    flexGrow: 1,
  },
  menuButton: {
    marginRight: theme.spacing(2),
  },
  title: {
    flexGrow: 1,
    display: 'none',
    [theme.breakpoints.up('sm')]: {
      display: 'block',
    },
  },
  search: {
    position: 'relative',
    borderRadius: theme.shape.borderRadius,
    backgroundColor: fade(theme.palette.common.white, 0.15),
    '&:hover': {
      backgroundColor: fade(theme.palette.common.white, 0.25),
    },
    marginLeft: 0,
    width: '100%',
    [theme.breakpoints.up('sm')]: {
      marginLeft: theme.spacing(1),
      width: 'auto',
    },
  },
  searchIcon: {
    width: theme.spacing(7),
    height: '100%',
    position: 'absolute',
    pointerEvents: 'none',
    display: 'flex',
    alignItems: 'center',
    justifyContent: 'center',
  },
  inputRoot: {
    color: 'inherit',
  },
  inputInput: {
    padding: theme.spacing(1, 1, 1, 7),
    transition: theme.transitions.create('width'),
    width: '100%',
    [theme.breakpoints.up('sm')]: {
      width: 120,
      '&:focus': {
        width: 200,
      },
    },
  },
}));

export default function SearchAppBar() {
  const classes = useStyles();

  return (
    <div className={classes.root}>
      <AppBar position="static">
        <Toolbar>
          <IconButton
            edge="start"
            className={classes.menuButton}
            color="inherit"
            aria-label="open drawer"
          >
            <MenuIcon />
          </IconButton>
          <Typography className={classes.title} variant="h6" noWrap>
            Material-UI
          </Typography>
          <div className={classes.search}>
            <div className={classes.searchIcon}>
              <SearchIcon />
            </div>
            <InputBase
              placeholder="Search…"
              classes={{
                root: classes.inputRoot,
                input: classes.inputInput,
              }}
              inputProps={{ 'aria-label': 'search' }}
            />
          </div>
        </Toolbar>
      </AppBar>
    </div>
  );
}

Answer 1

useStyles或makeStyles本身是material-ui提供的钩子，应位于功能组件内部。

import React from 'react'
import AppBar from '@material-ui/core/AppBar'
import Toolbar from '@material-ui/core/Toolbar'
import IconButton from '@material-ui/core/IconButton'
import Typography from '@material-ui/core/Typography'
import InputBase from '@material-ui/core/InputBase'
import { fade, makeStyles } from '@material-ui/core/styles'
import MenuIcon from '@material-ui/icons/Menu'
import SearchIcon from '@material-ui/icons/Search'

export default function SearchAppBar() {
    const classes = useStyles()

    return (
        <div className={classes.root}>
            <AppBar position="static">
                <Toolbar>
                    <IconButton
                        edge="start"
                        className={classes.menuButton}
                        color="inherit"
                        aria-label="open drawer">
                        <MenuIcon />
                    </IconButton>
                    <Typography className={classes.title} variant="h6" noWrap>
                        Material-UI
                    </Typography>
                    <div className={classes.search}>
                        <div className={classes.searchIcon}>
                            <SearchIcon />
                        </div>
                        <InputBase
                            placeholder="Search…"
                            classes={{
                                root: classes.inputRoot,
                                input: classes.inputInput
                            }}
                            inputProps={{ 'aria-label': 'search' }}
                        />
                    </div>
                </Toolbar>
            </AppBar>
        </div>
    )
}

const useStyles = makeStyles(theme => ({
    root: {
        flexGrow: 1
    },
    menuButton: {
        marginRight: theme.spacing(2)
    },
    title: {
        flexGrow: 1,
        display: 'none',
        [theme.breakpoints.up('sm')]: {
            display: 'block'
        }
    },
    search: {
        position: 'relative',
        borderRadius: theme.shape.borderRadius,
        backgroundColor: fade(theme.palette.common.white, 0.15),
        '&:hover': {
            backgroundColor: fade(theme.palette.common.white, 0.25)
        },
        marginLeft: 0,
        width: '100%',
        [theme.breakpoints.up('sm')]: {
            marginLeft: theme.spacing(1),
            width: 'auto'
        }
    },
    searchIcon: {
        width: theme.spacing(7),
        height: '100%',
        position: 'absolute',
        pointerEvents: 'none',
        display: 'flex',
        alignItems: 'center',
        justifyContent: 'center'
    },
    inputRoot: {
        color: 'inherit'
    },
    inputInput: {
        padding: theme.spacing(1, 1, 1, 7),
        transition: theme.transitions.create('width'),
        width: '100%',
        [theme.breakpoints.up('sm')]: {
            width: 120,
            '&:focus': {
                width: 200
            }
        }
    }
}))

使用Material UI反应钩子

1 个答案: