R Shiny alternate actionButton - r

Question

I have a simple app that each time click plus1, the value of x increases by 1, and each time click plus10, the value of x increases by 10. But I want plus10 can only be valid after plus1 is clicked. And after plus1 is clicked, plus10 can only be clicked once before being invalid again, which would require another click of plus1 to make it valid. So basically I want the user to click those two buttons alternately, with plus1 needs to be clicked first when the app is launched. Ideally, a warning would be given to the user if the user tried to click plus10 without clicking plus1 first: "Please click plus1 first".
library(shiny)
ui <- fluidPage(
actionButton("plus1", "+ 1"),
actionButton("plus10", "+ 10"),
textOutput("value")
)
server <- function(input, output, session) {
x = reactiveVal(0)
observeEvent(input$plus1,{
x(x()+1) # increment x by 1
})
observeEvent(input$plus10,{
x(x()+10) # increment x by 1
})
output$value = renderText(x())
}
shinyApp(ui, server)

Answer 1

This does what you want, but why do you want this?
library(shiny)
ui <- fluidPage(
actionButton("plus1", "+ 1"),
actionButton("plus10", "+ 10"),
textOutput("value"),
textOutput("warning")
)
server <- function(input, output, session) {
x = reactiveValues(x=0,click1=TRUE)
observeEvent(input$plus1,{
if (x$click1) {
x$x <- x$x+1 # increment x by 1
x$click1 <- !x$click1
} else {
output$warning <- renderText({"Please click plus10 first"})
}
})
observeEvent(input$plus10,{
if (!x$click1) {
x$x <- x$x+10 # increment x by 10
x$click1 <- !x$click1
} else {
output$warning <- renderText({"Please click plus1 first"})
}
})
output$value = renderText(x$x)
}
shinyApp(ui, server)
Let me know if explanation needed

Answer 2

Using shinyjs:
library(shiny)
library(shinyjs)
ui <- fluidPage(
useShinyjs(),
actionButton("plus1", "+ 1"),
disabled(actionButton("plus10", "+ 10")),
textOutput("value")
)
server <- function(input, output, session) {
x = reactiveVal(0)
observeEvent(input$plus1,{
x(x() +1 )
disable('plus1')
enable('plus10')
})
observeEvent(input$plus10, {
x(x() + 10)
enable('plus1')
disable('plus10')
})
output$value <- renderText({x()})
}
shinyApp(ui, server)

Answer 3

You can just another reactive value to track whether or not the user can add 10
library(shiny)
ui <- fluidPage(
actionButton("plus1", "+ 1"),
actionButton("plus10", "+ 10"),
textOutput("value")
)
server <- function(input, output, session) {
x <- reactiveVal(0)
canPlus10 <- reactiveVal(FALSE)
observeEvent(input$plus1,{
x(x()+1) # increment x by 1
canPlus10(TRUE)
})
observeEvent(input$plus10,{
if (canPlus10()) {
x(x()+10) # increment x by 10
} else {
showNotification("Please click +1 first")
}
canPlus10(FALSE)
})
output$value = renderText(x())
}
shinyApp(ui, server)