How can I get a button in Shiny to call both JavaScript and R code in parallel?

Question

I have an HTML button in Shiny that when clicked, calls the JavaScript function geocodeAddressStreet(...) in a .js file in the /www direct

Answer 1

So you want to have a button and when you click it, both a javascript function and some R code get called? I was able to do this with the onclick function from the shinyjs package (disclaimer: I wrote the package)

library(shinyjs)

jsCode <- "
shinyjs.geocodeAddr = function(params) {
  alert('JavaScript called!');
  // geocodeAddressStreet(...)
}
"

runApp(shinyApp(
  ui = fluidPage(
    useShinyjs(),
    extendShinyjs(text = jsCode),
    actionButton("btn", "Click me")
  ),
  server = function(input, output, session) {
    onclick("btn", {
      js$geocodeAddr()
      cat("R called as well")
    })
  }
))

Basically, the onclick function is an R function that will run when the button is clicked. Within it you can obviously call R code easily, but you can also call JS code using the shinyjs package -- that's how I made a call to js$geocodeAddr. Look at the extendShinyjs function. Alternatively, instead of using extendShinyjs(), you can also use the usual approach of session$sendCustomMessage(...)