@code {
    Chart<double?> chart;
    ChartTrendline<double?> chartTrendline;

    protected override async Task OnAfterRenderAsync( bool firstRender )
    {
        if ( firstRender )
        {
            await HandleRedraw();
        }
    }

    bool trendlinesOn = true;
    async Task OnButtonClicked()
    {
        trendlinesOn = !trendlinesOn;

        await HandleRedraw();
    }

    async Task HandleRedraw()
    {
        await chart.Clear();

        await chart.AddLabels( Labels );
        await chart.AddDataSet( GetLineChartDataset() );
        await chart.AddDataSet( GetLineChartDataset() );

        await chart.Update();

        // Add the trendline(s) after you have added the datasets and called await chart.Update();
        if ( trendlinesOn )
        {
            // This will add a trendline to the second dataset.
            // If you want to add it to the first dataset, set DatasetIndex = 0 (or don't set it at all as 0 is default)
            var trendlineData = new List<ChartTrendlineData>
            {
                new ChartTrendlineData
                {
                    DatasetIndex = 1,
                    Width = 10,
                    Color = ChartColor.FromRgba( 54, 162, 235, .6f )
                }
            };

            await chartTrendline.AddTrendLineOptions( trendlineData );
        }
    }

    LineChartDataset<double?> GetLineChartDataset()
    {
        return new LineChartDataset<double?>
            {
                Label = "# of randoms",
                Data = RandomizeData(),
                BackgroundColor = backgroundColors,
                BorderColor = borderColors,
                Fill = true,
                PointRadius = 2,
                BorderDash = new List<int> { }
            };
    }

    string[] Labels = { "0", "1", "2", "3", "4", "5" };
    List<string> backgroundColors = new List<string> { ChartColor.FromRgba( 255, 99, 132, 0.2f ), ChartColor.FromRgba( 54, 162, 235, 0.2f ), ChartColor.FromRgba( 255, 206, 86, 0.2f ), ChartColor.FromRgba( 75, 192, 192, 0.2f ), ChartColor.FromRgba( 153, 102, 255, 0.2f ), ChartColor.FromRgba( 255, 159, 64, 0.2f ) };
    List<string> borderColors = new List<string> { ChartColor.FromRgba( 255, 99, 132, 1f ), ChartColor.FromRgba( 54, 162, 235, 1f ), ChartColor.FromRgba( 255, 206, 86, 1f ), ChartColor.FromRgba( 75, 192, 192, 1f ), ChartColor.FromRgba( 153, 102, 255, 1f ), ChartColor.FromRgba( 255, 159, 64, 1f ) };

    List<double?> RandomizeData()
    {
        var r = new Random( DateTime.Now.Millisecond );

        return new List<double?> { r.Next( 3, 20 ) * r.NextDouble(), r.Next( 3, 30 ) * r.NextDouble(), r.Next( 3, 40 ) * r.NextDouble(), r.Next( 3, 50 ) * r.NextDouble(), r.Next( 3, 60 ) * r.NextDouble(), r.Next( 3, 70 ) * r.NextDouble() };
    }
}