basic plotly chart in a shiny app

basicChart.R

library("shiny")
library("plotly")
library("data.table")

dates <- seq(as.Date("2019-02-01"),length=12,by="months") - 1
books <- c(17,3,3,18,20,19,15,12,17,4,18,7)
laptops <- c(13,5,8,12,27,32,31,9,22,11,12,30)
tvs <- c(30,41,22,11,4,33,16,17,8,49,14,50)

data <- data.frame(dates = dates,
                  books = books,
                  laptops = laptops,
                  tvs = tvs)
data <- melt(data, id.vars = "dates")

server <- function(input, output) {
  
  output$sales = renderPlotly({
    fig <- plot_ly(data, x = ~dates, y = ~value, type = 'bar', name = ~variable, color = ~variable)
    fig <- fig %>% layout(xaxis = list(tickvals = dates, tickformat = "%b %Y", tickfont = list(size = 12)), barmode = 'stack')
    fig
  })

}

ui <- fluidPage(
  plotlyOutput("sales")
)

shinyApp(ui = ui, server = server)
shinyApp(ui = ui, server = server)