Reactivity of a Shiny actionButton() can be achieved in a few ways. #r #shiny

actionButton_eventReactive.R

library(shiny)

ui = basicPage(
  numericInput("n", "N:", min = 0, max = 100, value = 50),
  actionButton("submit", "Submit"),
  textOutput("print")
)

server = function(input, output) {
  ntext <- eventReactive(input$submit, { 
    input$n
  })
  
  output$print <- renderText({
    ntext()
  })
}

shinyApp(ui, server)

actionButton_observeEvent.R

library(shiny)

ui = basicPage(
  numericInput("n", "N:", min = 0, max = 100, value = 50),
  actionButton("submit", "Submit"),
  textOutput("print")
)
 
server = function(input, output) {
  observeEvent(input$submit, {
    output$print <- renderText({
      input$n
    })
  })
}

shinyApp(ui, server)

actionButton_reactiveValues.R

library(shiny)

ui = basicPage(
  numericInput("n", "N:", min = 0, max = 100, value = 50),
  actionButton("submit", "Submit"),
  textOutput("print")
)

server = function(input, output) {
  values <- reactiveValues(
    n = NULL
    )
  
  observeEvent(input$submit, {
    values$n <- input$n
  })
  
  output$print <- renderText({
    values$n
  })
}

shinyApp(ui, server)