echarts图例如何添加百分比

const pieChart = async () => {
  const myChart = echarts.init(piepic.value)
  const piedata = await getPieData(); // 等待数据返回
  myChart.setOption({
    title: {},
    grid: {},
    tooltip: {
      trigger: 'item',
    },
    legend: {
      top: 'middle',
      align:'left',
      icon: 'circle',
      textStyle: {
        fontSize: 12,
        padding: [0, 10, 0, -5] //图例文字内间距
      },
      orient: 'vertical',
      right:10,
      backgroundColor:'#f7f7f7',
      formatter: function (name) {
          var total = 0;
          var tarValue;
          for (var i = 0; i < piedata.length; i++) {
            total += piedata[i].value;
            if (name === piedata[i].name) {
              tarValue = piedata[i].value;
            }
          }
          var p = Math.round((tarValue / total) * 100);
          return name + p + "%";
        },
    },
    series: [
      {
        type: 'pie',
        radius: ['40%', '60%'],
        center: ['30%', '50%'],
        padAngle: 2,
        label: {
          show: false,
          position: 'center'
        },
        labelLine: {
          show: false
        },
        data:piedata,
      }
    ]
  })
}