document.addEventListener('DOMContentLoaded', function() { // Get div const plotDiv = document.querySelector('.plotly-graph-div'); // Setup callback plotDiv.on('plotly_hover', function(data){ const pointNumber = data.points[0].pointNumber; Plotly.Fx.hover(plotDiv, [ {curveNumber: 0, pointNumber: pointNumber}, {curveNumber: 1, pointNumber: pointNumber}, ],['xy','x2y2']); }); });