How to get Leaflet for R use 100% of Shiny dashboard height

I personally found, that setting the height relative to window-size is more satisfying. Height as percentage does not work, because the dashboardBody has undefined height. But relative to the whole document is okay.

100% of the dashoboardBody makes 100vh (ccs3-unit) minus header (minimum 50px) minus dashboardBody padding (2* 15px).

So, set the height to 100vh - 80px and you should be fine.

Since shiny does not support css3-units, this has to be included directly to the document, like in the code below.

library(shiny)
library(shinydashboard)
library(leaflet)

ui <- dashboardPage(
  dashboardHeader(),
  dashboardSidebar(),
  dashboardBody(
    tags$style(type = "text/css", "#map {height: calc(100vh - 80px) !important;}"),
    leafletOutput("map")
  )
)

server <- function(input, output) {
  output$map <- renderLeaflet({
    leaflet() %>% addTiles() %>% setView(42, 16, 4)
  })
}

runApp(shinyApp(ui, server), launch.browser = TRUE)

Have fun!

Another option is what jcheng5 and kent37 have described on GitHub

output$mymap = renderLeaflet({...make a map...})
leafletOutput('mymap', height=1000)

Works for me with a leaflet map in R flexdashboard