title: Get axis ranges after plotly resize in Shiny
body: <p>I have a Shiny app with a Plotly plot of time-series data. I want the user to be able to pan the x (time) axis, but keeping a consistent window of one day. To do this, <strong>I need to get the current x-axis range after each resize.</strong></p>
  
  <p>Why am I not just using a <code>rangeSlider</code>? Because I have about 25,000 data points, and using a <code>rangeSlider</code> requires loading all of the data into the plot when the app is initialized, which slows things down considerably. </p>