echarts多条折线图动态分层的实现方法

var xData = param.xData;

  var data = param.yData
  let option = [];
  let num =param.num ? param.num : 0;
  let max = num ? num *100 : 100;  //处理精度丢失问题 但不是最佳方案
option = {

    title: {
      left: 'center',
      text: param.title
    },
    tooltip: {
      trigger: 'axis',
    },
    legend: {
      right:0,
      data:param.tName,
    },
    grid: {
      left: '3%',
      right: '4%',
      bottom: '3%',
      containLabel: true
    },
    xAxis: {
      boundaryGap: false,
      data:param.xData
    },
    yAxis: {
      name: param.yName,
      splitLine: { show: false },
      
    },
    series: []
  }
  option[6].series.push(
    {
      name: '平行于y轴的趋势线',
      type: 'line',
      //data:[0],
      markLine: {
        silent: true,
        data: [{
          yAxis: num
        }]
      }
    }
  )
  if( param.option_type == 6){
    for( var item in param.yData){
      var obj ={
        name: param.yData[item].name,
        type: 'line',
        color:param.yData[item].color,
        data: param.yData[item].data
      }
      option[6].series.push(obj)
    }
  }