Aspnetcore.docs: Serious problems with syntax highlighting in *most* Blazor code samples

[danysdragons]

Issue description

I looked through all of the pages in the Blazor docs, and found the appearance of the C# code samples within @code blocks to be problematic. In only a small number of cases is syntax highlighting appropriately applied, and for the _vast majority_, syntax highlighting is absent entirely. There are issues with syntax highlighting outside @code blocks as well, but this is not as pervasive as the issues within @code _blocks._

Here's just one example: https://docs.microsoft.com/en-us/aspnet/core/blazor/data-binding?view=aspnetcore-3.1#child-to-parent-binding-with-chained-bind

Now that Blazor Web Assembly has been officially released, developers will expect a high level of polish in the corresponding documentation.

As developers, we spend much of our day looking at code in our IDEs that is fully syntax highlighted. So when reading documentation, code where syntax highlighting is faulty or absent entirely sticks out like a sore thumb, and gives the documentation an unpolished, unfinished look.

An example of a @code block:

It's not only @code blocks with this issue, here's some markup with weird looking syntax-coloring:

And again, this isn't a few isolated cases, it's like this _nearly everywhere_.

I should probably have submitted an issue earlier since I've noticed this for a while, but I assumed it would get polished up before the official release.

[Kryptos-FR]

It is not just the @code part, the whole highlighting theme is broken for that kind of code. The HTML part has sometimes three different colors for a tag.

[danysdragons]

I agree, I just emphasized @code since it stood out to me more. As for markup:

I think that's a good illustration of what you you described. I edited my issue description to emphasize that the problems aren't limited to @code blocks.

And again, this isn't a few isolated cases, it's like this _nearly everywhere_.

I've noticed this for a while, but assumed it would get polished up before the official release.

[guardrex]

@scottaddie are u aware of any current internal work on Razor/Blazor syntax highlighting?

[scottaddie]

@guardrex Closing as a duplicate of https://github.com/dotnet/AspNetCore.Docs/issues/17296. I'll follow up with engineering offline regarding updates on the situation. The docs currently use a fork of highlight.js, and the Razor language definition is incomplete. The result is the poor syntax highlighting that you're seeing.