Pfthb

I am modularizing my R Shiny app with custom Javascript functions using shinyjs package. I find defining parameters for js$functionName(params) useful and would like to also use it for shinyjs.init() that is automatically called when the app is initially loaded.

Clarification with JohnCoene's comment:

From the code below, I want to use customMessage defined within R used in shinyjs.init(). I want this because I have a pre-defined script that includes all hard-coded variables including HTML class names and IDs. I do not want to define another variable within shinyjs.init().

Please refer to the reproducible example using codes from the
shinyjs official page below:

library(shiny)
library(shinyjs)

customMessage <- 'The app has been launched'

jsCode <- '
shinyjs.init = function() 
 alert("I want to have a custom parameter for shinyjs.init()!");


shinyjs.backgroundCol = function(params) 
 var defaultParams = 
 id : null,
 col : "red"
 ;
 params = shinyjs.getParams(params, defaultParams);
 console.log(params);
 var el = $("#" + params.id);
 el.css("background-color", params.col);
'

shinyApp(
 ui = fluidPage(
 useShinyjs(),
 extendShinyjs(text = jsCode),
 p(id = "name", "My name is Dean"),
 p(id = "sport", "I like soccer"),
 selectInput("col", "Colour:",
 c("white", "yellow", "red", "blue", "purple")), 
 textInput("selector", "Element", ""),
 actionButton("btn", "Go")
 ),
 server = function(input, output) 
 observeEvent(input$btn, 
 js$backgroundCol(input$selector, input$col)
 )
 
)