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)    }  }