R markdown PDF: Temporarily hide spoiler code for quiz takers

Question

I am using R markdown to create a PDF R course. I want to insert a quiz like the following:

---
output: pdf_document
---

What is the class of the following R ob         


        

Answer 1

I wasn't thinking of a full shiny app, but something like this .Rmd

---
output: html_document
---

## q1 what is `class(pi)?`

<div id="spoiler" style="display:none">

```{r}
class(pi)
```

</div>

<button title="Click to show answer" type="button"
   onclick="if(document.getElementById('spoiler') .style.display=='none')
              {document.getElementById('spoiler') .style.display=''}
            else{document.getElementById('spoiler') .style.display='none'}">
  Show/hide
</button>

And then to click