改变图表类型，会出现两个图表.

[owenvip]

文档示例地址
修改如下：

class Demo extends React.Component {
  state = {
    type: 'interval',
  };
  onClick = () => {
    let { type } = this.state;
    type === 'interval' ? type = 'line' : type = 'interval';
    this.setState({ type });
  };
  render() {
    return (
      <div>
        <Chart height={300} width="100%" data={data} defs={defs} animate={{ type: 'scaley' }} pixelRatio={pixelRatio}>
          <Axis dataKey="year" label={{ fontSize: 8 }}/>
          <Axis dataKey="sales"/>
          <Tooltip showItemMarker={false} onShow={onShowTooltip}/>
          <Geom geom={this.state.type} position="year*sales"/>
          <Legend/>
        </Chart>
        <button onClick={this.onClick}>改变</button>
      </div>
    );
  }
}