ElementStacks

HTML

<script src="http://highcharts.com/js/testing.js"></script>
<div id="container" style="height: 400px"></div>

<button id="button">Get Y axis extremes</button>
<div id="report"></div>

JavaScript

var chart = new Highcharts.Chart({
    chart: {
        renderTo: 'container'
    },
    
    xAxis: {
        categories: ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec']
    },
    
    series: [{
        data: [29.9, 71.5, 106.4, 129.2, 144.0, 176.0, 135.6, 148.5, 216.4, 194.1, 95.6, 54.4]        
    }]
});


// the button action
$('#button').click(function() {
    var extremes = chart.yAxis[0].getExtremes()
    $('#report').html(
        'dataMax: '+ extremes.dataMax +'<br/>'+
        'dataMin: '+ extremes.dataMin +'<br/>'+
        'max: '+ extremes.max +'<br/>'+
        'min: '+ extremes.min +'<br/>'
    );
});