Fix removeEvent for native Shiny input containers - #283

Problem

removeEvent() does not remove handlers registered on native Shiny inputs such as textInput():

library(shiny)
library(shinyjs)
shinyApp(
  fluidPage(useShinyjs(), textInput("field", "Type here"),
            actionButton("remove", "Remove key handler"), textOutput("key")),
  function(input, output, session) {
    key <- reactiveVal("none")
    event_id <- onevent("keyup", "field", function(event) key(event$key))
    observeEvent(input$remove, {
      removeEvent(event_id, "field")
      key("removed")
    })
    output$key <- renderText(key())
  }
)

Type a key, click Remove, and type again: the supposedly removed callback still updates the output. Removing by event type has the same problem.

Attachment deliberately resolves native inputs to their .shiny-input-container, storing the handler IDs there. Removal looks for those IDs on the input itself and therefore leaves the handler active.

Change

Use the same existing container resolution in the existing-element removal path. This preserves selective instance removal, event-type removal, ordinary HTML elements and the queued dynamic-element path. Add a module fixture/regression covering instance removal without disturbing a second handler, removal by type, and ordinary paragraph events.

Validation

• R 4.3.3 / Shiny 1.8.0 / Chrome, real loopback Shiny sessions with normal DOM clicks/keypresses: base fails, patched code passes.
• The added fixture was exercised in Chrome using Playwright: on base the first/second input callbacks reach 3/3 despite removal, while patched values remain 1/2. Plain paragraph removal continues working; module namespaces are covered.
• Guide form and two-module visibility/state/reset/onclick flows plus extension initialization/parameters also pass in the real Shiny browser runtime.
• Source install, JavaScript syntax and diff checks pass.
• R CMD build --no-build-vignettes --no-manual and R CMD check --no-manual --no-vignettes with _R_CHECK_FORCE_SUGGESTS_=false: no errors; two warnings about unbuilt vignette outputs and one note for unavailable suggested packages (rmarkdown, shinyAce, shinydisconnect, shinytest2). Non-browser tests pass; the shinytest2 runner itself and full cross-platform/vignette checks were not run locally.

Summary by CodeRabbit

• Bug Fixes
  • Event handlers can now be reliably removed from Shiny inputs, including individual handlers and all handlers of a specified type.
• Tests
  • Added coverage for removing input and element event handlers and verifying the resulting behavior.