Allow the use of `browser()`

[DanChaltiel]

Hi,

First, thank you so much for this incredible extension!

This is kind of a minor issue, but I'm building a RevealJS presentation for teaching, and I'd like to show how we can use browser() to debug our scripts.

Using it on https://webr.sh/ works as expected, but calling it from the presentation throws this:

Error: Can't block for input when using the PostMessage communication channel.

This error is thrown regardless of where the call is made: in a function, a loop, or even the top level.

Is there a workaround I could use? Otherwise, is this something that can be fixed?

Thank you for your guidance.

[georgestagg]

There is a workaround, but it is a bit of a pain. You must use coi-serviceworker with your Quarto document to make the web page Cross-Origin Isolated. Once a page is isolated in this way, webR should use a different communication channel automatically, and browser() should work.

The procedure is to include the coi-serviceworker script with your Quarto project, and load it into the page using the yaml headers at the top of your Quarto document. This example repository: https://github.com/georgestagg/quarto-live-curl/ shows the procedure for a different extension, but the process is essentially the same.

[DanChaltiel]

Thank you very much for your quick response.

Unfortunately, it didn't work.
I tried including it using include-in-header like in your example, or using the following HTML chunk, either at the beginning or the end of my file.

<script src="assets/custom.js"></script>
<script src="assets/coi-serviceworker.min.js"></script>

In both cases, the file JS was loaded (I modified it to add a console.log() to be sure).
In the JS console, I get 2 lines that might be relevant here:

In case it matters, my presentation will be given live, so all I presented was run on RStudio in Windows 10. It will be shared on GH Pages in the future, but it doesn't matter if browser() can be used there, obviously.

[georgestagg]

so all I presented was run on RStudio in Windows 10

Would you mind trying to load the presentation in an external web browser, rather than in RStudio? I think you should be able to do this with the "Open in new Window" button in the preview pane.

[DanChaltiel]

Same result inside RStudio, on Chrome, and on Firefox.

[georgestagg]

Thanks for following up. I'll look into this further when I can.