Adding a pop-up window to an output

The addPopover() function from the shinyBS() package allows you to add pop-up windows to input or output elements within a shiny application. This is another one-liner, back in the server.R file, along with the function that draws the graph:

output$trend <- renderPlot({
  ...[functions from previous chapter]...
  if(input$smooth){
    thePlot <- thePlot + geom_smooth()
  }
  print(thePlot)
  addPopover(session, id = "trend", title = "Source",
    content = "All data from Google Analyics website at <a href =
    'http://example.com'>http://example.com</a>",
    trigger = 'click')
})

As you can see, addPopover() takes the session argument, which we gave to shinyServer() at the top, along with the ID of the element that we wish to annotate (trend) and a title (Source). Raw HTML can be passed straight in as in the preceding example.