3.0: Scripts and related static assets are now referenced as local files instead of using CDNs based on the current environment.

[Rick-Anderson]

See Scripts and related static assets are now referenced as local files instead of using CDNs based on the current environment.
in https://devblogs.microsoft.com/aspnet/asp-net-core-and-blazor-updates-in-net-core-3-0-preview-7/

We will provide samples and documentation for adding these features to new apps as needed.

[Rick-Anderson]

------------------- OUTLINE ------------------------------

• Create a new topic Add static assets from a CDN with the Environment Tag Helper
• TOC location Advanced/static-assets-cdn.md

Add static assets from a CDN with the Environment Tag Helper

The ASP.NET Core 1.x and 2.x web app templates used the [Environment Tag Helper](link here) to include static assets provided by various CDNs. One way to add CDN assets to an ASP.NET Core 3.0 and later app:

• Compare the ASP.NET Core 2.2 version of the template generated app with the 3.0 version.
• Add the markup removed from the 3.0 version.
• Update the version and Subresource Integrity (SRI) key.

Comparing 2.2 with 3.0 versions

Generate a 2.2 and 3.0 version of each desired template and compare the layout files. Alternatively, select the following links to download the layout file:

• MVC 2.2 and 3.0 layout files (provide link)
• Razor Pages 2.2 and 3.0 layout files (provide link)

Use a difference tool such as Visual Studio to compare the files.

The following image shows the Visual Studio generated difference of the ASP.NET Core 3.0 Razor Pages template layout file with the 2.2 version:

Show image here

The red boxes in the preceding image shows markup in the 2.2 Razor Pages layout file removed from the 3.0 version.

Show code snippets here they can copy/paste here

Update version numbers

Show them how to update static content. For example

• Go to https://cdnjs.com/
• Search on jquery.min.js
• use the Copy script tag to get the script reference and SRI key

[Rick-Anderson]

@danroth27 @scottaddie please review outline and priority

[Rick-Anderson]

@danroth27 @scottaddie please review outline and priority

[scottaddie]

Some thoughts:

• I agree with the P2 priority.
• Consider linking to the LibMan docs in an Additional resources section. It's an alternative approach to accessing static files from a CDN.
• As a time-constrained customer coming to the official docs, I wouldn't want to be told to generate and compare 2.2 to 3.0 projects to determine what changed. I'd expect the docs to provide that info.