响应度量图形在渲染时不显示

这是因为您没有在render方法中为metricgraphics组件提供属性,但是您已经将其添加到类的定义之前,而类的定义不起任何作用,只需删除它并将其粘贴到render方法中,如下所示

render() {
return (
  <div>
    <Hello name={this.state.name} />
    <p>
      Start editing to see some magic happen :)
    </p>
  <MetricsGraphics
    title="Downloads"
    description="This graphic shows a time-series of downloads."
    data={ [{'date':new Date('2014-11-01'),'value':12}, {'date':new Date('2014-11-02'),'value':18}] }
    width={600}
    height={250}
    x_accessor="date"
    y_accessor="value"
  />
  </div>
);
}