axisPointer.snap无效，坐标指示器无法吸附到最近的点上echarts 折线配置项内容和展示

文档里说snap=true时坐标指示器可以吸附到最近的点上。但实际使用中发现这个属性设置为true后没有任何变化，还是无法吸附。详见代码。期望的吸附效果参见：https://xueqiu.com/S/SH600016。

      var base = +new Date(1968, 9, 3);
var oneDay = 24 * 3600 * 1000;
var date = [];

var data = [];

var lastClose = 16.15;
for (var i = 1; i < 240; i++) {
    var now = new Date(base += oneDay);
    date.push([now.getFullYear(), now.getMonth() + 1, now.getDate()].join('/'));
    var delta = Math.round( Math.random() * 10 * lastClose) /100; 
    data.push(lastClose + delta);
}

var maxData = Math.max.apply(null, data);
var minData = Math.min.apply(null, data);
var maxDelta = Math.round( Math.max(maxData - lastClose, lastClose - minData) * 100) / 100;
var intervalY = Math.round(maxDelta * 100 / 3) / 100 ;
var minY = Math.round( (lastClose - intervalY * 4) * 100 ) / 100;
var maxY = Math.round( (lastClose + intervalY * 4) * 100 ) / 100;

var pminYtemp = Math.round( (maxY / lastClose - 1) * 10000 );
var pintervalY = Math.round( pminYtemp / 4 ) / 100;
var pmaxY = pintervalY * 4;
var pminY = pmaxY * -1 ;

//alert("pintervalY:" + pintervalY + ",pminY:" + pminY + ",pmaxY:" + pmaxY);

option = {
    tooltip: {
        trigger: 'axis',
        axisPointer: {
            type: 'cross',
            snap: true
        },
        position: function (pt) {
            return [pt[0], '10%'];
        }
    },
    title: {
        left: 'center',
        text: 'SH600016 民生银行',
    },
    toolbox: {
        feature: {
            dataZoom: {
                yAxisIndex: 'none'
            },
            restore: {},
            saveAsImage: {}
        }
    },
    xAxis: {
        type: 'category',
        boundaryGap: false,
        axisPointer: {
            show: true,
            type: 'line',
            snap: true
        },
        data: date
    },
    yAxis: [
    {
        min: minY,
        max: maxY,
        interval: intervalY,
        type: 'value',
        axisPointer: {
            show: true,
            type: 'line',
            snap: true
        },
        splitLine:{
            lineStyle:{
                color: ['#ccc','#ccc','#ccc','#ccc','red']
            }
        },
        axisLabel:{
            textStyle: {
                color: function (value, index) {
                    return value >= lastClose ? 'red' : 'green';
                }
            }
        },
        axisTick:{
            inside:'true'
        }
    },
    {
        min: pminY,
        max: pmaxY,
        interval: pintervalY,
        type: 'value',
        axisLabel:{
            formatter: '{value}%',
            textStyle: {
                color: function (value, index) {
                    return value >= 0 ? 'red' : 'green';
                }
            }
        },
        axisPointer: {
            snap: true,
            label:{
                formatter: '{value}%'
            }
        },
        axisTick:{
            inside:'true'
        }
    }
    ],
    axisPointer:{
        show: true,
        type: 'line',
        snap: true
    },
    dataZoom: [{
        type: 'inside',
        start: 0,
        end: 240
    }, {
        start: 0,
        end: 240,
        handleIcon: 'M10.7,11.9v-1.3H9.3v1.3c-4.9,0.3-8.8,4.4-8.8,9.4c0,5,3.9,9.1,8.8,9.4v1.3h1.3v-1.3c4.9-0.3,8.8-4.4,8.8-9.4C19.5,16.3,15.6,12.2,10.7,11.9z M13.3,24.4H6.7V23h6.6V24.4z M13.3,19.6H6.7v-1.4h6.6V19.6z',
        handleSize: '80%',
        handleStyle: {
            color: '#fff',
            shadowBlur: 3,
            shadowColor: 'rgba(0, 0, 0, 0.6)',
            shadowOffsetX: 2,
            shadowOffsetY: 2
        }
    }],
    series: [
        {
            name:'模拟数据',
            type:'line',
            smooth:true,
            symbol: 'none',
            sampling: 'average',
            itemStyle: {
                normal: {
                    color: 'rgb(255, 70, 131)'
                }
            },
            areaStyle: {
                normal: {
                    color: new echarts.graphic.LinearGradient(0, 0, 0, 1, [{
                        offset: 0,
                        color: 'rgb(255, 158, 68)'
                    }, {
                        offset: 1,
                        color: 'rgb(255, 70, 131)'
                    }])
                }
            },
            data: data
        }
    ]
};