highcharts控制X刻度值整数调整

function chartData() {
        var app_id = $('.app_id').attr('app_id');
        var gener_id = $('.gener_id').attr('gener_id');
        var pop_id = $('.listType li.active').attr('pop_id');
        var date = $(".realTimeDate li.active span").attr("date");
        $.ajax({
            url:'/app/rankChange',
            type:'post',
            data:{
                app_id:app_id,
                gener_id:gener_id,
                pop_id:pop_id,
                date:date,
            },
            success:function (data) {
                chartLoad(data.data)
            },
            dataType:'json'
        })
    }

	var arr = [];
	var arr1 = [];
    function chartLoad(data){
        var gener_name = $(".gener_id").text();
		console.log(data);

		for(var i=0;i<data.rank_app_list.length;i++){
			console.log(data.rank_total_list[i]);
			arr.push(data.rank_app_list[i]);
			i = i+2;
		}
		for(var k=0;k<data.rank_total_list.length;k++){
			console.log(data.rank_total_list[k]);
			arr1.push(data.rank_total_list[k]);
			k = k+2;
		}
        $('#container').highcharts({
            //tooltip控制折线图
            tooltip:{
                shared: true,//控制多个产品共同显示内容
                crosshairs: true,//让y轴坐标显示
            },
            credits: {
                enabled: false//去掉链接
            },
            exporting:{
                enabled:false //用来设置是否显示‘打印’,'导出'等功能按钮，不设置时默认为true
            },
            //折线图颜色
            colors:['#33CC99','#FF6565'],
            title: {
                text: '排名趋势'
            },
            xAxis:{
                // gridLineWidth : 1
                // inverted: Boolean
                categories: ["0:00","3:00","6:00","9:00","12:00","15:00","18:00","21:00","00:00"],
                showFirstLabel: true,
                reversed: false
            },
            yAxis:[
                {
                    title: {
                        text: '应用榜排名'
                    },
                    reversed: true
                },
                {
                    title: {
                        text: gener_name+'排名'
                    },
                    reversed: true,
                    opposite: true
                }
            ],
            legend: {
                layout: 'vertical',
                layout: 'horizontal',
                align: 'center',
                verticalAlign: 'bottom',
                x: 0,
                y: 0
            },
            plotOptions: {
                series: {
                    label: {
                        connectorAllowed: true,
                    },
                    pointStart: 1,//时间刻度值  X轴坐标
                }
            },
            series: [{
                yAxis:0,
                name: '应用总榜',
                data: arr1
            }, {
                yAxis:1,
                name: gener_name,
                data: arr
            }],
            responsive: {
                rules: [{
                    condition: {
                        maxWidth: 300
                    },
                    chartOptions: {
                        legend: {
                            layout: 'horizontal',
                            align: 'center',
                            verticalAlign: 'bottom'
                        }
                    }
                }]
            }
        });
    }
chartData()