index

The index for the series, which will affect the visibility of the series:

dataSeries: [
    {
        seriesType: 'splinearea',
        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],
        index: 3
    }
]

This setting is demonstrated in the following example.