Question

When I hover a point with the mouse, the point is highlighted. Is it possible to highlight the whole series in place of the single point?
An example in jfiddle:

$(function () {
    var chart;
    $(document).ready(function() {
        chart = new Highcharts.Chart({
            chart: {
                renderTo: 'container'
            },
            series: [{
                type: 'line',
                data: [[0, 1.11], [1, 4.51], [2, 4]],
            },{
                type: 'line',
                data: [[0, 2.11], [1, 3.51], [2, 2]],
            }]
        });
    });

});

Answer 1

You can change the line width of the series as it is described in the api:

http://api.highcharts.com/highcharts#plotOptions.series.states.hover.lineWidth

plotOptions: {
            series: {
                states: {
                    hover: {
                        enabled: true,
                        lineWidth: 5
                    }
                }
            }
        },