legend: {
            type: 'scroll',
            orient: 'vertical',
            x: 'left',
            y: 'bottom',
            top: "42%",
            left: '13%',
            data: this.dutyNames,
            textStyle: { color: '#fff' },
            triggerEvent: true,
            tooltip: {
              show: true,
              trigger: 'item',//鼠标移动上去展示全称
            },
            formatter: function (params) {
              var val = "";
              if (params.length > 6) {
                val = params.substr(0, 16) + '...';
                return val;
              } else {
                return params;
              }
            }
     },

显示效果：