web worker bundle DCE-d incorrectly in an SPA project

[diegopego]

I wrote a web worker sample and got this error on the developer tools console:

Uncaught TypeError: Cannot read properties of undefined (reading 'prototype')

I used this template:
dotnet new websharper-spa -lang f# -n MySPA

namespace MySPA

open WebSharper
open WebSharper.JavaScript
open WebSharper.UI
open WebSharper.UI.Client
open WebSharper.UI.Templating

[<JavaScript>]
module Client =
    // The templates are loaded from the DOM, so you just can edit index.html
    // and refresh your browser, no need to recompile unless you add or remove holes.
    type IndexTemplate = Template<"wwwroot/index.html", ClientLoad.FromDocument>

    let People =
        ListModel.FromSeq [
            "John"
            "Paul"
        ]

    [<SPAEntryPoint>]
    let Main () =
        let myWorker = new Worker(fun self ->
            Console.Log "This was written from the worker!"
            self.PostMessage("This worker's job is done, it can be terminated.")
        )
        
        myWorker.Onmessage <- fun event ->
            Console.Log event.Data
            myWorker.Terminate()

        let newName = Var.Create ""

        IndexTemplate.Main()
            .ListContainer(
                People.View.DocSeqCached(fun (name: string) ->
                    IndexTemplate.ListItem().Name(name).Doc()
                )
            )
            .Name(newName)
            .Add(fun _ ->
                People.Add(newName.Value)
                newName.Value <- ""
            )
            .Doc()
        |> Doc.RunById "main"

[Jand42]

@diegopego Thanks for the report!

This must be a problem with web workers defined within an SPA project. When bundling runs for the web worker, WebSharper mistakenly also includes the all the code based on SPAEntryPoint in the MySPA.worker.js bundle too, which in this case has WS.UI stuff using DOM Elements, not available in web worker context.

To fix: web worker bundling should ignore the SPAEntryPoint and JavaScriptExport attributes.

[granicz]

Well, just to be clear, this needs a compiler fix.

[diegopego]

I'm always willing to learn more in order to help. Thank you!

[Jand42]

@diegopego Thanks for the report, I have pushed small fix, will do a CI build soon