R shiny router redirect to URL containing parameters

I want to perform redirect to URL with parameters, like https://www.google.com.tw/webhp?newwindow=1, which works well in basic shiny app as below:

library(shiny)
jscode <- "Shiny.addCustomMessageHandler('mymessage', function(message) {window.location = 'https://www.google.com.tw/webhp?newwindow=1';});"

ui <- fluidPage(
  tags$head(tags$script(jscode)),     
  checkboxInput("Redirect","Redirect",value = T)
)

server <- function(input, output, session) {

  observeEvent(input$Redirect,{
    if(!input$Redirect){
      session$sendCustomMessage("mymessage", "mymessage")
    }
  })
}

shinyApp(ui,server)

However, it does not work when under the scope of shiny.router, please see code as below for more detail. My final goal is only redirect to side page containing parameters. Thanks in advance.

library(shiny)
library(shiny.router)

jscode <- "Shiny.addCustomMessageHandler('mymessage', function(message) {window.location = 'https://www.google.com.tw/webhp?newwindow=1';});"

# This generates menu in user interface with links.
menu <- (
  tags$ul(
    tags$li(a(class = "item", href = route_link("home"), "Home page")),
    tags$li(a(class = "item", href = route_link("side"), "Side page"))
  )
)

# This creates UI for each page.
page <- function(title, content) {
  div(
    menu,
    titlePanel(title),
    p(content),
    actionButton("switch_page", "Click to switch page!")
  )
}

# Both sample pages.
home_page <- page("Home page", uiOutput("current_page"))
side_page <- page("Side page", uiOutput("current_page"))

# Creates router. We provide routing path, a UI as
# well as a server-side callback for each page.
router <- make_router(
  route("home", home_page, NA),
  route("side", side_page, NA)
)

# Create output for our router in main UI of Shiny app.
ui <- shinyUI(fluidPage(
  router_ui()
))

server <- shinyServer(function(input, output, session) {
  router(input, output, session)

  output$current_page <- renderText({
    page <- get_page(session)
    sprintf("Welcome on %s page!", page)
  })

  observeEvent(input$switch_page, {
    if (is_page("home")) {
      #change_page("side")
      session$sendCustomMessage("mymessage", "mymessage")
    } else if (is_page("side")) {
      change_page("home")
    }
  })
})

shinyApp(ui, server)