React两个bug踩坑

ReactDOM

import React from 'react';
import App from './App';

React.ReactDOM.render(<App />, document.getElementById('root'));
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console报错render找不到，这是因为react已经把ReactDOM分离出来，这样引用会出错，改为

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

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

return 错误

console错误信息

Nothing was returned from render. This usually means a return statement is missing. Or, to render nothing, return null
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这是因为代码中return同一行没有代码

render(){
    return 
    (
      <div>
        <p>App test</p>
      </div>)
  }
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改为

render(){
    return (
      <div>
        <p>App test</p>
      </div>)
  }
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后正常