[Solved]-Highchart: can I make sure the values on the Y axis are only integers?-Highcharts

Try to null all values in xAxis or use following code.

xAxis: {
        categories: ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun',
            'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'],
        labels: {
            enabled: false
        }
    }

Please see the example http://jsfiddle.net/ssgoanb5/

See the Doc: http://api.highcharts.com/highcharts#xAxis.labels.enabled

New Updates:

For avoiding decimals values on graph Axis(x/y), Add allowDecimals attributes.

See the Doc. http://api.highcharts.com/highcharts#yAxis.allowDecimals

yAxis: {
        allowDecimals: false,
        title: {
            text: 'Temperature (°C)'
        },
        plotLines: [{
            value: 0,
            width: 1,
            color: '#808080'
        }]
    }

Please check the updated JSfiddle: http://jsfiddle.net/ssgoanb5/6/