Rstudio为啥不出图？

[luffyye8670]

请帮忙看下，RStudiod不显示图，代码如下

library(shiny)
library(shinydashboard)
library(recharts)

ui<-fluidPage(
box(eChartOutput("chart"),width = NULL)
)

server <- function(input, output,session) {
output$chart<-renderEChart({
df2 <- data.frame(
saleNum=c(10,20,30,40,50,60,70,15,25,35,45,55,65,75,25,35,45,55,65,75,85),
seller=c(rep("Yellow",7), rep("Red",7), rep("White",7)),
weekDay = c(rep(c("Mon","Tue","Wed","Thu","Fri","Sat","Sun"),3)),
stringsAsFactors =FALSE
)
eBar(dat= df2, xvar=~weekDay, yvar=~saleNum, series=~seller)
})
}

shinyApp(ui, server)