缩小删除日期，但保留时间

Question

当我放大图表时，可以看到类似的日期，26 Apr, 9:05但是当我缩小图表时，只能看到类似的时间9:00。如何一直显示日期？这是我的图（https://codepen.io/anon/pen/GLPPGq）：

am4core.useTheme(am4themes_animated);

var chart = am4core.create("chartdiv", am4charts.XYChart);

chart.dataSource.url = "https://api.myjson.com/bins/i3np8";

chart.dataSource.events.on("parseended", function(ev) {

    var data = ev.target.data;

    data.sort(function(lhs, rhs) {

        return lhs.time - rhs.time;

    });

    data.forEach(function(item) {

        item.time *= 1000;

    });

});

chart.numberFormatter.numberFormat = "#.0b";

chart.dateFormatter.inputDateFormat = "x";

var dateAxis = chart.xAxes.push(new am4charts.DateAxis());

dateAxis.dateFormats.setKey("minute", "d MMM, \nHH:mm");

dateAxis.periodChangeDateFormats.setKey("minute", "d MMM, \nHH:mm");

dateAxis.startLocation = 0.5;

dateAxis.endLocation = 0.5;

var valueAxis = chart.yAxes.push(new am4charts.ValueAxis());

valueAxis.tooltip.disabled = true;

var series = chart.series.push(new am4charts.LineSeries());

series.dataFields.dateX = "time";

series.name = "Traffic out";

series.dataFields.valueY = "outDiffFormatted";

series.tooltipHTML = "<span style='font-size:14px; color:#000000;'><b>{valueY.value}</b></span>";

series.tooltipText = "[#000]{valueY.value}[/]";

series.tooltip.background.fill = am4core.color("#FFF");

series.tooltip.getStrokeFromObject = true;

series.tooltip.background.strokeWidth = 3;

series.tooltip.getFillFromObject = false;

series.fillOpacity = 0.6;

series.strokeWidth = 2;

series.stacked = false;