Trick-event-ui

Trick-event-ui.r

# This part of the code generates the user interface show at the client's side.
# For details and tutorials go to http://shiny.rstudio.com

ui <- shinyUI(fluidPage(
  # This adds a tiny bit of javascript to the client side's web page.
  # It defines a global variable 'negator', which is negated when
  # the javascript function negate() is called.
  # This can be used to trick Shiny's event observers.
  tags$head(tags$script("var negator=1;
                        function negate() {
                        negator = -negator
                        return(negator)
                        }")),

  # A custom user interface element:
  # If you click me twice in a row, the second time, nothing will happen:
  p(a("I'm a custom interface",       href = "#",
        onclick = "Shiny.onInputChange(\"customInterface\", 1);"),
      "clicking me twice won't work as intended..."),
  
  # Another custom user interface element:
  # If you click me twice in a row, the siny server will respond (because
  # the value that is being passed is negated):
  p(a("I'm another custom interface", href = "#",
        onclick = "Shiny.onInputChange(\"customInterface\", 2*negate());"),
      "clicking me twice will work as intended..."),

  # Output text will be shown here:
  verbatimTextOutput("outputText"),
  p("Source code is shown below")
))