tooltip formatter 回调问题

描述:当前是关于Echarts图表中的 柱状图 示例。
 
            var labelRight = {
    position: 'right'
};
option = {
    title: {
        text: '交错正负轴标签',
        subtext: 'From ExcelHome',
        sublink: 'http://e.weibo.com/1341556070/AjwF2AgQm'
    },
    tooltip: {
        trigger: 'axis',
        axisPointer: {            // 坐标轴指示器log,坐标轴触发有效
            type: 'shadow'        // 默认为直线,可选为:'line' | 'shadow'
        },
         formatter: function (params, ticket, callback) {
             console.log(params,'test'); 
             callback(ticket,'777');// 这里回调会被执行很多遍
             return "loading";
         }
    },
    grid: {
        top: 80,
        bottom: 30
    },
    xAxis: {
        type: 'value',
        position: 'top',
        splitLine: {
            lineStyle: {
                type: 'dashed'
            }
        }
    },
    yAxis: {
        type: 'category',
        axisLine: {show: false},
        axisLabel: {show: false},
        axisTick: {show: false},
        splitLine: {show: false},
        data: ['ten', 'nine', 'eight', 'seven', 'six', 'five', 'four', 'three', 'two', 'one']
    },
    series: [
        {
            name: '生活费',
            type: 'bar',
            stack: '总量',
            label: {
                show: true,
                formatter: '{b}'
            },
            data: [
                {value: -0.07, label: labelRight},
                {value: -0.09, label: labelRight},
                0.2, 0.44,
                {value: -0.23, label: labelRight},
                0.08,
                {value: -0.17, label: labelRight},
                0.47,
                {value: -0.36, label: labelRight},
                0.18
            ]
        }
    ]
};