R shiny: how to clear an input field with a default value using shinyjs?

Question

I'm trying to use the shinyjs package to clear and disable an input field that has a default value in my shiny app. The clear/disable button seems to work. However, when I click submit, the default value is still being submitted (see picture below). How can I make it submit a NULL or an empty string?

library(shinyjs)
library(shiny)

# this is supposed to change the input value to null
jsCode <- 'shinyjs.clear_input = function(params){
    var defaultParams = {
    input_id : null
  };
  params = shinyjs.getParams(params, defaultParams);
  var el = $("#" + params.input_id);
    el.val(null);}'

  shinyApp(

    ui = fluidPage(
      useShinyjs(),  
      extendShinyjs(text = jsCode, functions = c("clear_input")),
      textInput("input",  label = "input", value = "default text"),
      actionButton("clear", label = "clear/disable"),
      actionButton("submit", "submit"),
      tags$div(id="result")
      ),
    server = function(input, output) {
      
      observeEvent(input$clear, {
        js$clear_input("input")
        disable("input")
      })

      observeEvent(input$submit, {
        insertUI("#result", ui=renderText(input$input))
      })
    }
  )

Answer 1

Personally, I am not very comfortable with javascript so I try to avoid as much as possible and do it in R. You can use updateTextInput to update the values in textInput.

library(shiny)
library(shinyjs)

shinyApp(
  ui = fluidPage(
    useShinyjs(),
    textInput("input",  label = "input", value = "default text"),
    actionButton("clear", label = "clear/disable"),
    actionButton("submit", "submit"),
    tags$div(id="result")
  ),
  server = function(input, output, session) {
    
    observeEvent(input$clear, {
      updateTextInput(session, "input", value = "")
      disable("input")
    })
    
    observeEvent(input$submit, {
      insertUI("#result", ui=renderText(input$input))
    })
  }
)