webr chunks in a document with shiny

[sachsmc]

I'm having some difficulty getting webr to work in a document with some shiny reactive elements, that I run with quarto serve. Here is an simple example. When I run this with quarto serve, the webr chunk is missing. If I remove the shiny stuff and run with quarto preview, the webr chunk appears as expected. I'm not seeing any error messages in the javascript console. Any ideas what might be going wrong?

---
title: "Testing"
format: html
server: shiny
filters:
  - webr
---


## Webr

```{r}
rnorm(1)
```


```{webr}
fit = lm(mpg ~ am, data = mtcars)
summary(fit)
```



## shiny

```{r}
library(shiny)
sliderInput("bins", "Number of bins:", 
            min = 1, max = 50, value = 30)
plotOutput("distPlot")
```

```{r}
#| context: server
output$distPlot <- renderPlot({
  x <- faithful[, 2]  # Old Faithful Geyser data
  bins <- seq(min(x), max(x), length.out = input$bins + 1)
  hist(x, breaks = bins, col = 'darkgray', border = 'white')
})
```

[coatless]

What server: shiny is doing is suppressing the echo of all code cells. So, if the code cell is set to echo: true, then the webR box should open up. Thus, with this knowledge we now have:

However, the Shiny app embedded in Quarto is not able to find the necessary .js files. I've tried placing them in /js, /www, and _files to no avail based on:

https://quarto.org/docs/interactive/shiny/resources.html#asset-resources

Please note, we need the echo component as quarto extensions come into play in the later stage of the render where pandoc is:

With this being said, if you can figure out where the Shiny app is launching from, I can try and figure out how to make sure the worker files are in the correct location by default for the server:shiny backend.

Feel free to explore with:

---
title: "Testing with Shiny Backend"
format: html
keep-md: true
server: shiny
filters:
  - webr
---

```{r}
knitr::knit_engines$set(webr = knitr:::eng_verbatim)
```

## Webr

```{r}
rnorm(1)
```

Note, we added the `#| echo: true` remark:

```{webr}
#| echo: true
1 + 1
```

## shiny

```{r}
library(shiny)

sliderInput("bins", "Number of bins:", 
            min = 1, max = 50, value = 30)
plotOutput("distPlot")
```

```{r}
#| context: server
output$distPlot <- renderPlot({
  x <- faithful[, 2]  # Old Faithful Geyser data
  bins <- seq(min(x), max(x), length.out = input$bins + 1)
  hist(x, breaks = bins, col = 'darkgray', border = 'white')
})
```

[sachsmc]

Thanks for your response. I tried the following and it seems that it is able to find the worker files:

1. Put the webr-worker.js and webr-servicework.js files in a js/ subdirectory
2. Modify line 21 of the webr-init.html file to:
   globalThis.webR = new WebR({SW_URL: 'js/'});

Then when I run quarto serve test.qmd, I can see the following messages in the javascript console:

webR service worker installed serviceworker.ts:15
webR service worker activating serviceworker.ts:15

However the Run button seems to be stuck at "Loading webR...", and I am never able to run the R code. Does this give you any clues? Could it be something in the shiny javascript code that is blocking the webR? Sorry, I am no js expert.