angular5使用echart渐变色功能

options = {
      backgroundColor: ‘#fff‘,
      xAxis: {
        type: ‘category‘,
        boundaryGap: false,
        data: xValue,
      },
      yAxis: {
        type: ‘value‘
      },
      series: [{
        data: [820, 932, 901, 934, 1290, 1330, 1320],
        type: ‘line‘,
        itemStyle: {
          color: ‘#00CD9F‘
        },
        areaStyle: {
          color: new (<any>echarts).graphic.LinearGradient(0, 0, 0, 1, [{
            offset: 0,
            color: ‘rgba(0,205,159,0.2)‘
          }, {
            offset: 1,
            color: ‘rgba(0,232,205,0)‘
          }])
        }
      }]
    };