simple slider update demo

server.r

library(datasets)

shinyServer(function(input, output) {
  
  output$mSlider <- renderUI({
    
    input$updateSlider
    
    Range  <- sample(1:100)[1:2]
    Lambda <- runif(1)
    Value  <- Lambda*Range[1] + (1-Lambda)*(Range[2])
  
    sliderInput("mInput",label = "slider input",min = min(Range), max = max(Range), value =Value )
  })
  
})
     

ui.r

library(shiny)

shinyUI(fluidPage(
  
    fluidRow(
      br(),
      h1("update slider example")
    ),
    fluidRow(
      column(2,        
        uiOutput("mSlider"),      
        actionButton(inputId = "updateSlider", "update slider")
      )    
    )
  )
)