Scheduled Invalidation
Schedules the current reactive context to be invalidated in the given number of milliseconds.
invalidateLater(millis, session = getDefaultReactiveDomain())
millis |
Approximate milliseconds to wait before invalidating the current reactive context. |
session |
A session object. This is needed to cancel any scheduled
invalidations after a user has ended the session. If |
If this is placed within an observer or reactive expression, that object will
be invalidated (and re-execute) after the interval has passed. The
re-execution will reset the invalidation flag, so in a typical use case, the
object will keep re-executing and waiting for the specified interval. It's
possible to stop this cycle by adding conditional logic that prevents the
invalidateLater from being run.
reactiveTimer() is a slightly less safe alternative.
## Only run examples in interactive R sessions
if (interactive()) {
ui <- fluidPage(
sliderInput("n", "Number of observations", 2, 1000, 500),
plotOutput("plot")
)
server <- function(input, output, session) {
observe({
# Re-execute this reactive expression after 1000 milliseconds
invalidateLater(1000, session)
# Do something each time this is invalidated.
# The isolate() makes this observer _not_ get invalidated and re-executed
# when input$n changes.
print(paste("The value of input$n is", isolate(input$n)))
})
# Generate a new histogram at timed intervals, but not when
# input$n changes.
output$plot <- renderPlot({
# Re-execute this reactive expression after 2000 milliseconds
invalidateLater(2000)
hist(rnorm(isolate(input$n)))
})
}
shinyApp(ui, server)
}Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.