echarts 的series有多个对象，如何实现tooltip的轮播

要实现tooltip的轮播，可以通过以下步骤：

1. 在tooltip的formatter函数中，获取当前数据的数量和索引，并将其保存到变量中。

formatter: function(params) {
  var dataIndex = params.dataIndex;
  var dataCount = params.seriesData.length;
  ...
}

2. 在tooltip的axisPointer的showContent属性中，设置轮播的定时器，并在定时器中更新tooltip的内容，并调用轮播函数。

axisPointer: {
  type: 'shadow',
  show: true,
  handle: {
    show: true,
    margin: 30
  },
  showContent: true,
  triggerOn: 'mousemove',
  formatter: function(params) {
    var dataIndex = params.dataIndex;
    var dataCount = params.seriesData.length;
    var content = '';
    var current = dataIndex;
    var timer = setInterval(function() {
      current = (current + 1) % dataCount;
      content = '内容' + current;
      chart.dispatchAction({
        type: 'showTip',
        seriesIndex: params.seriesIndex,
        dataIndex: current
      });
      chart.dispatchAction({
        type: 'highlight',
        seriesIndex: params.seriesIndex,
        dataIndex: current
      });
      setTimeout(function() {
        chart.dispatchAction({
          type: 'hideTip'
        });
        chart.dispatchAction({
          type: 'downplay',
          seriesIndex: params.seriesIndex,
          dataIndex: current
        });
      }, 2000);
    }, 3000);
    return content;
  }
}

3. 在轮播函数中，先通过dispatchAction方法显示当前数据的tooltip，并高亮当前数据。然后等待2秒钟后，再通过dispatchAction方法隐藏tooltip，并取消当前数据的高亮状态。

function carousel(params, chart) {
  var dataIndex = params.dataIndex;
  var dataCount = params.seriesData.length;
  var current = dataIndex;
  setInterval(function() {
    current = (current + 1) % dataCount;
    chart.dispatchAction({
      type: 'showTip',
      seriesIndex: params.seriesIndex,
      dataIndex: current
    });
    chart.dispatchAction({
      type: 'highlight',
      seriesIndex: params.seriesIndex,
      dataIndex: current
    });
    setTimeout(function() {
      chart.dispatchAction({
        type: 'hideTip'
      });
      chart.dispatchAction({
        type: 'downplay',
        seriesIndex: params.seriesIndex,
        dataIndex: current
      });
    }, 2000);
  }, 3000);
}

4. 在图表初始化后，调用轮播函数。

var chart = echarts.init(document.getElementById('main'));
...
chart.on('showTip', function(params) {
  clearInterval(carouselTimer);
});
chart.on('hideTip', function(params) {
  carouselTimer = setInterval(function() {
    carousel(params, chart);
  }, 3000);
});
...
var carouselTimer = setInterval(function() {
  carousel(params, chart);
}, 3000);

完整代码示例：

var option = {
  tooltip: {
    trigger: 'axis',
    axisPointer: {
      type: 'shadow',
      show: true,
      handle: {
        show: true,
        margin: 30
      },
      showContent: true,
      triggerOn: 'mousemove',
      formatter: function(params) {
        var dataIndex = params.dataIndex;
        var dataCount = params.seriesData.length;
        var content = '';
        var current = dataIndex;
        var timer = setInterval(function() {
          current = (current + 1) % dataCount;
          content = '内容' + current;
          chart.dispatchAction({
            type: 'showTip',
            seriesIndex: params.seriesIndex,
            dataIndex: current
          });
          chart.dispatchAction({
            type: 'highlight',
            seriesIndex: params.seriesIndex,
            dataIndex: current
          });
          setTimeout(function() {
            chart.dispatchAction({
              type: 'hideTip'
            });
            chart.dispatchAction({
              type: 'downplay',
              seriesIndex: params.seriesIndex,
              dataIndex: current
            });
          }, 2000);
        }, 3000);
        return content;
      }
    }
  },
  series: [{
    type: 'bar',
    data: [10, 20, 30, 40, 50]
  }]
};

var chart = echarts.init(document.getElementById('main'));
chart.setOption(option);

function carousel(params, chart) {
  var dataIndex = params.dataIndex;
  var dataCount = params.seriesData.length;
  var current = dataIndex;
  setInterval(function() {
    current = (current + 1) % dataCount;
    chart.dispatchAction({
      type: 'showTip',
      seriesIndex: params.seriesIndex,
      dataIndex: current
    });
    chart.dispatchAction({
      type: 'highlight',
      seriesIndex: params.seriesIndex,
      dataIndex: current
    });
    setTimeout(function() {
      chart.dispatchAction({
        type: 'hideTip'
      });
      chart.dispatchAction({
        type: 'downplay',
        seriesIndex: params.seriesIndex,
        dataIndex: current
      });
    }, 2000);
  }, 3000);
}

chart.on('showTip', function(params) {
  clearInterval(carouselTimer);
});

chart.on('hideTip', function(params) {
  carouselTimer = setInterval(function() {
    carousel(params, chart);
  }, 3000);
});

var carouselTimer = setInterval(function() {
  carousel(params, chart);
}, 3000);