How to access the current mode from modeBarButtonsToAdd

Hi,

I have added a button to the modebar to change the current the mode of the graph.

        { 
            displaylogo: false,
            responsive: true,
            modeBarButtonsToAdd: 
            [{
                name: 'Trace markers toggler',        
                icon: icon1,        
                click: function(graphContainer) {
                            

                    Plotly.restyle(graphContainer, {mode: 'lines+markers'})
        
                }
            }]
        }

I would like to toggle the mode from lines to lines+markers and viceversa, but I don’t know how to access the current mode. Any help?