Fix: Allow users to opt out of shiny's download autoenable

[elnelson575]

Motivation

In v1.9.0 (#4041), Shiny began automatically enabling downloadButton()/downloadLink() once the server's downloadHandler is ready. This is a good default — it prevents users from clicking a download button before the server can handle it.

However, this auto-enable creates a problem for apps that want to keep a download button disabled until some condition is met (e.g., the user selects a dataset first). Before #4041, apps could render the button as disabled and use shinyjs::enable()/shinyjs::disable() (or custom JS) to manage its state. Now, the auto-enable unconditionally overrides that disabled state as soon as the downloadHandler initializes.

Closes #4119. Also likely fixes daattali/shinyjs#277.

Solution

Add an enabled parameter to downloadButton() and downloadLink() with three possible values:

• "auto" (default): Current behavior — starts disabled, auto-enables when the downloadHandler is ready. No breaking change.
• TRUE: Starts enabled immediately, without waiting for the server. Useful when you know the handler will be ready and don't want the brief disabled flash.
• FALSE: Starts disabled and Shiny will never auto-enable it. You manage the enabled/disabled state yourself (e.g., via shinyjs).

Additionally, when enabled = "auto", Shiny now detects if shinyjs has independently disabled the element (via the shinyjs-disabled class) and skips the auto-enable in that case. This means shinyjs::disabled() in the UI and shinyjs::disable() from the server both work correctly without any explicit opt-out.

Implementation details

• A data-shiny-disable-auto-enable attribute is added to the element when enabled is TRUE or FALSE (i.e., any non-"auto" value). The client-side renderValue checks for this attribute (and for shinyjs-disabled) before enabling.
• Clicks on disabled download links are now properly blocked via CSS pointer-events: none (previously, a disabled-looking anchor link could still be clicked).

Also used by rstudio/bslib#1298.

App example

Screen.Recording.2026-04-23.at.6.33.35.PM.mov

Sample demo app

library(shinyjs)

# This app tests all permutations of enabled x shinyjs disable method,
# for both downloadButton and downloadLink.

code_block <- function(...) {
  tags$pre(style = "background:#f5f5f5; padding:10px; margin:0;", tags$code(...))
}

case_row <- function(heading, description = NULL, controls, code) {
  tagList(
    h4(heading),
    if (!is.null(description)) p(description),
    fluidRow(
      column(4, controls),
      column(8, code_block(code))
    )
  )
}

ui <- fluidPage(
  useShinyjs(),

  h2("downloadButton: enabled x shinyjs permutations"),

  hr(),
  h3('enabled = "auto" (default)'),

  case_row(
    "Case 1: No shinyjs — should AUTO-ENABLE once server is ready",
    NULL,
    downloadButton("btn_1", "Download"),
    'downloadButton("btn_1", "Download")'
  ),

  br(),
  case_row(
    "Case 2: shinyjs::disabled() in UI — stays disabled until toggled",
    controls = tagList(
      actionButton("toggle_btn_2", "Toggle"),
      br(), br(),
      disabled(downloadButton("btn_2", "Download"))
    ),
    code = 'disabled(
  downloadButton("btn_2", "Download")
)

# server:
observeEvent(input$toggle_btn_2, {
  if (input$toggle_btn_2 %% 2 == 1) enable("btn_2") else disable("btn_2")
})'
  ),

  br(),
  case_row(
    "Case 3: shinyjs::disable() from server — auto-enables, then disable/enable on toggle",
    "When disabled, renderValue should not override it.",
    tagList(
      actionButton("toggle_btn_3", "Toggle"),
      br(), br(),
      downloadButton("btn_3", "Download")
    ),
    'downloadButton("btn_3", "Download")

# server:
observeEvent(input$toggle_btn_3, {
  if (input$toggle_btn_3 %% 2 == 1) disable("btn_3") else enable("btn_3")
})'
  ),

  hr(),
  h3("enabled = TRUE (explicit pre-enable)"),

  case_row(
    "Case 4: No shinyjs — starts enabled immediately (before server), stays enabled",
    NULL,
    downloadButton("btn_4", "Download", enabled = TRUE),
    'downloadButton("btn_4", "Download", enabled = TRUE)'
  ),

  br(),
  case_row(
    "Case 5: shinyjs::disabled() in UI — starts disabled, toggle enables/disables",
    controls = tagList(
      actionButton("toggle_btn_5", "Toggle"),
      br(), br(),
      disabled(downloadButton("btn_5", "Download", enabled = TRUE))
    ),
    code = 'disabled(
  downloadButton("btn_5", "Download", enabled = TRUE)
)

# server:
observeEvent(input$toggle_btn_5, {
  if (input$toggle_btn_5 %% 2 == 1) enable("btn_5") else disable("btn_5")
})'
  ),

  br(),
  case_row(
    "Case 6: shinyjs::disable() from server — starts enabled, disable/enable on toggle",
    "Disabled state should be preserved after renderValue fires.",
    tagList(
      actionButton("toggle_btn_6", "Toggle"),
      br(), br(),
      downloadButton("btn_6", "Download", enabled = TRUE)
    ),
    'downloadButton("btn_6", "Download", enabled = TRUE)

# server:
observeEvent(input$toggle_btn_6, {
  if (input$toggle_btn_6 %% 2 == 1) disable("btn_6") else enable("btn_6")
})'
  ),

  hr(),
  h3("enabled = FALSE (explicit opt-out)"),

  case_row(
    "Case 7: No shinyjs — should STAY DISABLED",
    NULL,
    downloadButton("btn_7", "Download", enabled = FALSE),
    'downloadButton("btn_7", "Download", enabled = FALSE)'
  ),

  br(),
  case_row(
    "Case 8: shinyjs::disabled() in UI — stays disabled until toggled",
    "Toggle should enable on first click, then disable on the next.",
    tagList(
      actionButton("toggle_btn_8", "Toggle"),
      br(), br(),
      disabled(downloadButton("btn_8", "Download", enabled = FALSE))
    ),
    'disabled(
  downloadButton("btn_8", "Download", enabled = FALSE)
)

# server:
observeEvent(input$toggle_btn_8, {
  if (input$toggle_btn_8 %% 2 == 1) enable("btn_8") else disable("btn_8")
})'
  ),

  br(),
  case_row(
    "Case 9: shinyjs::disable() from server — stays disabled until toggled",
    NULL,
    tagList(
      actionButton("toggle_btn_9", "Toggle"),
      br(), br(),
      downloadButton("btn_9", "Download", enabled = FALSE)
    ),
    'downloadButton("btn_9", "Download", enabled = FALSE)

# server:
observeEvent(input$toggle_btn_9, {
  if (input$toggle_btn_9 %% 2 == 1) enable("btn_9") else disable("btn_9")
})'
  ),

  h2("downloadLink: enabled x shinyjs permutations"),

  hr(),
  h3('enabled = "auto" (default)'),

  case_row(
    "Case 10: No shinyjs — should AUTO-ENABLE once server is ready",
    NULL,
    downloadLink("lnk_1", "Download"),
    'downloadLink("lnk_1", "Download")'
  ),

  br(),
  case_row(
    "Case 11: shinyjs::disabled() in UI — stays disabled until toggled",
    controls = tagList(
      actionButton("toggle_lnk_2", "Toggle"),
      br(), br(),
      disabled(downloadLink("lnk_2", "Download"))
    ),
    code = 'disabled(
  downloadLink("lnk_2", "Download")
)

# server:
observeEvent(input$toggle_lnk_2, {
  if (input$toggle_lnk_2 %% 2 == 1) enable("lnk_2") else disable("lnk_2")
})'
  ),

  br(),
  case_row(
    "Case 12: shinyjs::disable() from server — auto-enables, then disable/enable on toggle",
    "When disabled, renderValue should not override it.",
    tagList(
      actionButton("toggle_lnk_3", "Toggle"),
      br(), br(),
      downloadLink("lnk_3", "Download")
    ),
    'downloadLink("lnk_3", "Download")

# server:
observeEvent(input$toggle_lnk_3, {
  if (input$toggle_lnk_3 %% 2 == 1) disable("lnk_3") else enable("lnk_3")
})'
  ),

  hr(),
  h3("enabled = TRUE (explicit pre-enable)"),

  case_row(
    "Case 13: No shinyjs — starts enabled immediately (before server), stays enabled",
    NULL,
    downloadLink("lnk_4", "Download", enabled = TRUE),
    'downloadLink("lnk_4", "Download", enabled = TRUE)'
  ),

  br(),
  case_row(
    "Case 14: shinyjs::disabled() in UI — starts disabled, toggle enables/disables",
    controls = tagList(
      actionButton("toggle_lnk_5", "Toggle"),
      br(), br(),
      disabled(downloadLink("lnk_5", "Download", enabled = TRUE))
    ),
    code = 'disabled(
  downloadLink("lnk_5", "Download", enabled = TRUE)
)

# server:
observeEvent(input$toggle_lnk_5, {
  if (input$toggle_lnk_5 %% 2 == 1) enable("lnk_5") else disable("lnk_5")
})'
  ),

  br(),
  case_row(
    "Case 15: shinyjs::disable() from server — starts enabled, disable/enable on toggle",
    "Disabled state should be preserved after renderValue fires.",
    tagList(
      actionButton("toggle_lnk_6", "Toggle"),
      br(), br(),
      downloadLink("lnk_6", "Download", enabled = TRUE)
    ),
    'downloadLink("lnk_6", "Download", enabled = TRUE)

# server:
observeEvent(input$toggle_lnk_6, {
  if (input$toggle_lnk_6 %% 2 == 1) disable("lnk_6") else enable("lnk_6")
})'
  ),

  hr(),
  h3("enabled = FALSE (explicit opt-out)"),

  case_row(
    "Case 16: No shinyjs — should STAY DISABLED",
    NULL,
    downloadLink("lnk_7", "Download", enabled = FALSE),
    'downloadLink("lnk_7", "Download", enabled = FALSE)'
  ),

  br(),
  case_row(
    "Case 17: shinyjs::disabled() in UI — stays disabled until toggled",
    "Toggle should enable on first click, then disable on the next.",
    tagList(
      actionButton("toggle_lnk_8", "Toggle"),
      br(), br(),
      disabled(downloadLink("lnk_8", "Download", enabled = FALSE))
    ),
    'disabled(
  downloadLink("lnk_8", "Download", enabled = FALSE)
)

# server:
observeEvent(input$toggle_lnk_8, {
  if (input$toggle_lnk_8 %% 2 == 1) enable("lnk_8") else disable("lnk_8")
})'
  ),

  br(),
  case_row(
    "Case 18: shinyjs::disable() from server — stays disabled until toggled",
    NULL,
    tagList(
      actionButton("toggle_lnk_9", "Toggle"),
      br(), br(),
      downloadLink("lnk_9", "Download", enabled = FALSE)
    ),
    'downloadLink("lnk_9", "Download", enabled = FALSE)

# server:
observeEvent(input$toggle_lnk_9, {
  if (input$toggle_lnk_9 %% 2 == 1) enable("lnk_9") else disable("lnk_9")
})'
  )
)

server <- function(input, output, session) {
  make_handler <- function(label) {
    downloadHandler(
      filename = paste0(label, ".txt"),
      content = function(file) writeLines(paste("File from", label), file)
    )
  }

  for (i in 1:9) output[[paste0("btn_", i)]] <- make_handler(paste0("btn_", i))
  for (i in 1:9) output[[paste0("lnk_", i)]] <- make_handler(paste0("lnk_", i))

  observeEvent(input$toggle_btn_2, {
    if (input$toggle_btn_2 %% 2 == 1) enable("btn_2") else disable("btn_2")
  })
  observeEvent(input$toggle_btn_3, {
    if (input$toggle_btn_3 %% 2 == 1) disable("btn_3") else enable("btn_3")
  })
  observeEvent(input$toggle_btn_5, {
    if (input$toggle_btn_5 %% 2 == 1) enable("btn_5") else disable("btn_5")
  })
  observeEvent(input$toggle_btn_6, {
    if (input$toggle_btn_6 %% 2 == 1) disable("btn_6") else enable("btn_6")
  })
  observeEvent(input$toggle_btn_8, {
    if (input$toggle_btn_8 %% 2 == 1) enable("btn_8") else disable("btn_8")
  })
  observeEvent(input$toggle_btn_9, {
    if (input$toggle_btn_9 %% 2 == 1) enable("btn_9") else disable("btn_9")
  })
  observeEvent(input$toggle_lnk_2, {
    if (input$toggle_lnk_2 %% 2 == 1) enable("lnk_2") else disable("lnk_2")
  })
  observeEvent(input$toggle_lnk_3, {
    if (input$toggle_lnk_3 %% 2 == 1) disable("lnk_3") else enable("lnk_3")
  })
  observeEvent(input$toggle_lnk_5, {
    if (input$toggle_lnk_5 %% 2 == 1) enable("lnk_5") else disable("lnk_5")
  })
  observeEvent(input$toggle_lnk_6, {
    if (input$toggle_lnk_6 %% 2 == 1) disable("lnk_6") else enable("lnk_6")
  })
  observeEvent(input$toggle_lnk_8, {
    if (input$toggle_lnk_8 %% 2 == 1) enable("lnk_8") else disable("lnk_8")
  })
  observeEvent(input$toggle_lnk_9, {
    if (input$toggle_lnk_9 %% 2 == 1) enable("lnk_9") else disable("lnk_9")
  })
}

shinyApp(ui, server)

[cpsievert]

@copilot resolve the merge conflicts in this pull request

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✅ elnelson575
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[Copilot]

@copilot resolve the merge conflicts in this pull request

Resolved and pushed in 4c0548e. I merged origin/main into this branch and resolved the conflict in DESCRIPTION by keeping both Config/Needs/check: shinyjs, shinytest2 and Config/roxygen2/version: 8.0.0. Screenshot: N/A (no UI changes in this conflict-only update).

[cpsievert]

Thanks @elnelson575. Please also make a py-shiny PR with the equivalent changes

[Copilot]

Pull request overview

Copilot reviewed 12 out of 15 changed files in this pull request and generated 2 comments.