I use Shinyalert. In the text option I want to use Html together with JC. this is my code:

observeEvent(input[["btn"]], {
    shinyalert(
        title = "title",
        html = TRUE,
        text =  
            HTML("<p id='demo'></p><script>",
                  JC('document.getElementById("demo").innerHTML =  6;'),
                  "</script>"
                )
    )
})

But it doesn't work. what is my problem?