Custom handlers Example Code

app.R

library(shiny)
library(bs4Dash)

insertMessageItem <- function(item, session = shiny::getDefaultReactiveDomain()) {
  session$sendCustomMessage("add-message-item", message = as.character(item))
}

dropdownDeps <- function(){
  htmltools::htmlDependency(name = "bs4-dropdown",
                            version = "1.0.0",
                            src = c(file = "."),
                            script = "add-message-item.js")
}

ServerFunction <- function(input, output, session) {

    observeEvent(input$add, {
      insertMessageItem(
        messageItem(
          message = paste("message", input$add),
          image = "https://adminlte.io/themes/v3/dist/img/user2-160x160.jpg",
          from = "Divad Nojnarg",
          time = "today",
          color = "success"
        )
      )
    })

}