echarts 折线图背景色渐变

// 填充区域的样式
          areaStyle: {
            normal: {
              // 填充色渐变
              color: new echarts.graphic.LinearGradient(0, 0, 0, 1, [
                { offset: 0, color: "#3aa7ff" },
                { offset: 0.5, color: "rgba(58, 167, 255,0.4)" },
                { offset: 1, color: "rgba(58, 167, 255,0)" }
              ])
            }
          },

效果图：