react项目中为什么报createElement未定义

Question

入口文件

import React from 'react';
import ReactDOM from 'react-dom';
import './index.css';
import App from './contain/app.jsx';
import { Provider } from 'react-redux';
import registerServiceWorker from './registerServiceWorker';
import configureStore from './store/configureStore';
const store = configureStore();

ReactDOM.render(
  <Provider store={store}>
    <App/>
  </Provider>
  , document.getElementById('root'));
registerServiceWorker();

容器组件

import { React, Component } from 'react';

import { connect } from 'react-redux'

import consoleLog from '../actions/index'
import Com from '../components/component-a/index.jsx'
import './app.css'

class App extends Component {
  render() {
    const { dispatch } = this.props;
    return (
      <div className="App">
        <header className="App-header">
          <h1 className="App-title">Welcome to React</h1>
        </header>
        <p className="App-intro">
          To get started, edit <code>src/App.js</code> and save to reload.
        </p>
        <Com dispatchAction={ text => dispatch(consoleLog(text))}/>
      </div>
    )
  }
}

const mapStateToProps = (state) => {
  return {
    text: state.text
  }
}
const mapDispatchToProps = (dispatch) => {
  return {
    dispatchAction: () => {
      dispatch({type: 'CONSOLE'})
    }
  }
}
export default connect(mapStateToProps, mapDispatchToProps)(App);

<Com>组件

import { React, Component} from 'react'
import { findDOMNode} from 'react-dom'

export default class com extends Component {
  render () {
    return (
      <div>
        <input type="text" ref= 'input'/>
        <button onClick={ e => this.handleClick(e)}>add</button>
      </div>
    )
  }
  handleClick (e) {
    const inputNode = findDOMNode(this.refs.input);
    const text = inputNode.value.trim();
    this.props.dispatchAction(text);
    inputNode.value = '';
  }
}

错误信息

Answer 1

import { React, Component } from 'react';应该写成import React, { Component } from 'react'