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% Generated by roxygen2 (4.1.0): do not edit by hand
% Please edit documentation in R/reactives.R
\name{invalidateLater}
\alias{invalidateLater}
\title{Scheduled Invalidation}
\usage{
invalidateLater(millis, session)
}
\arguments{
\item{millis}{Approximate milliseconds to wait before invalidating the
current reactive context.}
\item{session}{A session object. This is needed to cancel any scheduled
invalidations after a user has ended the session. If \code{NULL}, then
this invalidation will not be tied to any session, and so it will still
occur.}
}
\description{
Schedules the current reactive context to be invalidated in the given number
of milliseconds.
}
\details{
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
\code{invalidateLater} from being run.
}
\examples{
\dontrun{
shinyServer(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$plot <- renderPlot({
# Re-execute this reactive expression after 2000 milliseconds
invalidateLater(2000, session)
hist(isolate(input$n))
})
})
}
}
\seealso{
\code{\link{reactiveTimer}} is a slightly less safe alternative.
}
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