When are bundle Date Modified values created?

Question

With ASP.NET Bundling and Minification at what point is the Date Modified Header Response value created?

Assuming I'm not using a caching service and have browser cache disabled, are the bundles dynamically created on each page load and therefore generate a new Date Modified value?

Answer 1

There are few checks done by browser.

1. Browser will first checks for css/js/images in local cache. And if content found with valid expiration date then it will use it directly to render.
2. If content found but it has expired validity then browser will ask server to check do you have new content I am having content of xxxx date with xxx eTag.
3. If there is no change in content on server then server will return status=304 with last modified. and browser will use same cached version to render
4. If there is change then server will return new content with status=200. and browser will use new content to render.