Question

I am creating a HighChart with a plotLine in it. The plotLine has a fixed value, while the data can vary between charts.

HighChart scales the y-axis automatically based on the maximum value of data, but it doesn’t consider the plotLine’s value in its calculations.

Hence, if the data range encompasses the plotLine value, the plotLine gets shown, but gets cropped out of the viewport if not.

Example:

    $(function () {
        $(document).ready(function() {
            var chart = new Highcharts.Chart({
                chart: {
                    renderTo: 'container',
                    type: 'column'
                },
                title: {
                    text: 'Dummy Data by Region'
                },
                xAxis: {
                    categories: ['Africa', 'America', 'Asia']
                },
                yAxis: {
                    plotLines:[{
                        value:450,
                        color: '#ff0000',
                        width:2,
                        zIndex:4,
                        label:{text:'goal'}
                    }]
                },
                series: [{
                    name: 'Year 1800',
                    data: [107, 31, 650]
                }]
            });
        });
        
    });​

JSFiddle for above code: http://jsfiddle.net/4R5HH/3/

The goal line (in red) is shown for the default data, but if I change the data to [107, 31, 250], then the plotLine goes out of the graph viewport and hence becomes invisible.

Answer 1

You need to add in a point to you chart but disable the marker.
I added a new series with scatter plot type and its value equal to the goal value:

{
     name: 'Goal',
     type: 'scatter',
     marker: {
          enabled: false
     },
     data: [450]
}

See updated jsFiddle: http://jsfiddle.net/wergeld/4R5HH/4/