给无状态的纯UI组件应用样式

请保持样式远离那些离不开state的组件. 比如路由, 视图, 容器, 表单, 布局等等不应该有任何的样式或者css class出现在组件上.
相反, 这些复杂的业务组件应该有一些带有基本功能的无状态UI组件组成.

没有任何样式/classNames的Form组件, 仅有纯的组件组合而成.

class SampleComponent extends Component {
  render() {
    return (
      <form onSubmit={this.handleSubmit}>
        <Heading children='Sign In'/>
        <Input
          name='username'
          value={username}
          onChange={this.handleChange}/>
        <Input
          type='password'
          name='password'
          value={password}
          onChange={this.handleChange}/>
        <Button
          type='submit'
          children='Sign In'/>
      </form>
    )
  }
}
// 表达组件(带样式)
const Button = ({
  ...props
  }) => {
  const sx = {
    fontFamily: 'inherit',
    fontSize: 'inherit',
    fontWeight: 'bold',
    textDecoration: 'none',
    display: 'inline-block',
    margin: 0,
    paddingTop: 8,
    paddingBottom: 8,
    paddingLeft: 16,
    paddingRight: 16,
    border: 0,
    color: 'white',
    backgroundColor: 'blue',
    WebkitAppearance: 'none',
    MozAppearance: 'none'
  }
  return (
    <button {...props} style={sx}/>
  )
}