What is the problem with For loop in shinyjs in r?

Question

I can not figure out how to make For loop work in javascript inside Shiny R application using shinyjs library. Working script stops functioning if I add any For loop inside the script.

The minimal example code demonstrating the issue is below. Uncommenting For loop (removing /* and */ lines) makes the code non-functional.

Please have a look. Thank you.

library(shiny)
library(shinyjs)

ui <- fluidPage(
  # pressing this button increments counter
  actionButton("button", "press"),
  # text showing counter value
  textOutput("text"),
  # place to store the javascript
  uiOutput("default"),
  useShinyjs()
)

server <- function(input, output, session) {
  counter <- 1
  output$default <- renderUI({
    # this script sends current value of the counter back to Shiny as input$result
    # For loop is dot doing anything
    # if For loop is inside comment - the script works
    # if the loop is not commented - the script does not work
    tags$script("
                Shiny.addCustomMessageHandler('bttn_pressed', function(value) {
                  var i;
                  /*
                  for (i = 0; i < 2; i++) {
                  }
                  */
                  Shiny.setInputValue('result', value, {priority: 'event'});
                });"
    )
  })
  
  # update text output with the value reported by javascript
  observeEvent(input$result, {
    output$text <- renderText({input$result})
  })
  
  # increment the counter and send the updated value to javascript
  observeEvent(input$button, {
    counter <<- counter + 1
    session$sendCustomMessage("bttn_pressed", counter)
  })
}

shinyApp(ui = ui, server = server)