SpaProxy should not inject middleware with ASPNETCORE_HOSTINGSTARTUPASSEMBLIES

[jez9999]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

I wanted to post in this bug: #45130

But it's been locked to me even though I created it. I was asked there by @javiercn as to what problems I run into with the new ASP.NET SPA approach that puts express.js in front of the ASP.NET server, so for the record I'd like to note two things:

1. I like to be able to modify the index.html page in the pipeline so that I can inject JavaScript into the page to provide configuration information from the ASP.NET app
2. I like to be able to selectively inject JS into the index.html page so that I can eg. only inject Google Analytics on the production server.

It seems to me that unless ASP.NET has ultimate control over serving the index.html page, I'm unable to do that with the new mechanism.

Expected Behavior

No response

Steps To Reproduce

No response

Exceptions (if any)

No response

.NET Version

No response

Anything else?

No response

[javiercn]

I like to be able to modify the index.html page in the pipeline so that I can inject JavaScript into the page to provide configuration information from the ASP.NET app.

Is it not possible to add a script reference to the page, and generate the config from an endpoint that serves that file as a script?

I like to be able to selectively inject JS into the index.html page so that I can eg. only inject Google Analytics on the production server.

Is there a reason why the mechanisms that angular/react provide are not enough to achieve this?

[jez9999]

I like to be able to modify the index.html page in the pipeline so that I can inject JavaScript into the page to provide configuration information from the ASP.NET app.

Is it not possible to add a script reference to the page, and generate the config from an endpoint that serves that file as a script?

Yes, or for that matter, to pull it from a separate REST API request, but it results in a completely unnecessary HTTP request. Data's already being sent down for the original page request and customizing it is the most efficient way to customize the behaviour.

I like to be able to selectively inject JS into the index.html page so that I can eg. only inject Google Analytics on the production server.

Is there a reason why the mechanisms that angular/react provide are not enough to achieve this?

The environment is an ASP.NET-specific setting of which angular/react are not aware.

In addition. GA4 tells you to insert its analytics script using a script async tag:

<script async src="https://www.googletagmanager.com/gtag/js?id=G-12345"></script>
<script>
	window.dataLayer = window.dataLayer || [];
	function gtag() { dataLayer.push(arguments); }
	gtag('js', new Date());
	gtag('config', 'G-12345');
</script>

I'm not entirely sure how to do that using pure JS, or what the consequences would be for the async nature of the script loading if it were done that way instead of just pasting the markup. Nor is it a way of adding the Analytics that's supported by Google as far as I can tell. Obviously, just rendering that markup or not rendering it is a reliable way to turn it on or off, however.

We've moved this issue to the Backlog milestone. This means that it is not going to be worked on for the coming release. We will reassess the backlog following the current release and consider this item at that time. To learn more about our issue management process and to have better expectation regarding different types of issues you can read our Triage Process.