添加组件程序后，在反应js中编译

Question

当我向我的应用程序添加对话框窗口组件时不起作用。我是新人，所以我有很多问题 这是我的对话框类：

/* eslint-disable react/no-multi-comp */

import React from 'react';
import PropTypes from 'prop-types';
import { withStyles } from '@material-ui/core/styles';
import Button from '@material-ui/core/Button';
import Avatar from '@material-ui/core/Avatar';
import List from '@material-ui/core/List';
import ListItem from '@material-ui/core/ListItem';
import ListItemAvatar from '@material-ui/core/ListItemAvatar';
import ListItemText from '@material-ui/core/ListItemText';
import DialogTitle from '@material-ui/core/DialogTitle';
import Dialog from '@material-ui/core/Dialog';
import PersonIcon from '@material-ui/icons/Person';
import AddIcon from '@material-ui/icons/Add';
import Typography from '@material-ui/core/Typography';
import blue from '@material-ui/core/colors/blue';

const emails = ['username@gmail.com', 'user02@gmail.com'];
const styles = {
    avatar: {
        backgroundColor: blue[100],
        color: blue[600],
    },
};

class SimpleDialog extends React.Component {
    handleClose = () => {
        this.props.onClose(this.props.selectedValue);
    };

    handleListItemClick = value => {
        this.props.onClose(value);
    };

    render() {
        const { classes, onClose, selectedValue, ...other } = this.props;

        return (
            <Dialog onClose={this.handleClose} aria-labelledby="simple-dialog-title" {...other}>
                <DialogTitle id="simple-dialog-title">Set backup account</DialogTitle>
                <div>
                    <List>
                        {emails.map(email => (
                            <ListItem button onClick={() => this.handleListItemClick(email)} key={email}>
                                <ListItemAvatar>
                                    <Avatar className={classes.avatar}>
                                        <PersonIcon />
                                    </Avatar>
                                </ListItemAvatar>
                                <ListItemText primary={email} />
                            </ListItem>
                        ))}
                        <ListItem button onClick={() => this.handleListItemClick('addAccount')}>
                            <ListItemAvatar>
                                <Avatar>
                                    <AddIcon />
                                </Avatar>
                            </ListItemAvatar>
                            <ListItemText primary="add account" />
                        </ListItem>
                    </List>
                </div>
            </Dialog>
        );
    }
}

SimpleDialog.propTypes = {
    classes: PropTypes.object.isRequired,
    onClose: PropTypes.func,
    selectedValue: PropTypes.string,
};

const SimpleDialogWrapped = withStyles(styles)(SimpleDialog);

class SimpleDialogDemo extends React.Component {
    state = {
        open: false,
        selectedValue: emails[1],
    };

    handleClickOpen = () => {
        this.setState({
            open: true,
        });
    };

    handleClose = value => {
        this.setState({ selectedValue: value, open: false });
    };

    render() {
        return (
            <div>
                <Typography variant="subheading">Selected: {this.state.selectedValue}</Typography>
                <br />
                <Button onClick={this.handleClickOpen}>Open simple dialog</Button>
                <SimpleDialogWrapped
                    selectedValue={this.state.selectedValue}
                    open={this.state.open}
                    onClose={this.handleClose}
                />
            </div>
        );
    }
}

export default SimpleDialogDemo;

当我在我的主要调用此方法时，我有这个错误：

ERROR in ./SimpleDialog.jsx
Module build failed: SyntaxError: C:/Projekt/crew/crew-ui/SimpleDialog.jsx: Unexpected token (28:16)

  26 | 
  27 | class SimpleDialog extends React.Component {
> 28 |     handleClose = () => {
     |                 ^
  29 |         this.props.onClose(this.props.selectedValue);
  30 |     };
  31 | 

 @ ./main.js 11:20-49
 @ multi (webpack)-dev-server/client?http://localhost:8080 webpack/hot/dev-server ./main.js

有时当我在这个课程中添加一些其他组件时，开始工作。例如，当我添加textfield materia-ui组件时。请求帮助

在我的package.json中，我有：

 "babel-loader": "^7.1.4",

我添加这个，因为当我看到这个错误时，人们写道我应该有这个。但这没有帮助。