Cannot render flow chart in R shiny

Question

I want to display a flow chart in shiny, it just not showing in shiny browsers, but displays in the viewer pane in rstudio.

library(shiny)
library(DiagrammeR)

ui <- fluidPage(
  plotOutput(outputId ="temp")
)

server <- function(input, output, session) {
  plotInput = function(){
    DiagrammeR(paste('graph LR',
                     sprintf("A(%s)-->B", iris[1,1]),
                     sep = ';'))
  }

  output$temp<-renderPlot(
    plotInput()
  )
}

shinyApp(ui, server)