ASP.NET MVC: When does script bundling decide to change the version of a bundle?

Question

I used to put "?v=n" at the end of my scripts references, like:

<script type="text/javascript" src="@Url.Content("~/Scripts/Foo.js")?v=2"></script>

Each time I edited a .js, I added 1 to that versioning, eg:

<script type="text/javascript" src="@Url.Content("~/Scripts/Foo.js")?v=3"></script>

I decided this couldn't continue being like that (I have too many scripts now), so I started using the ASP.NET MVC bundling feature (BundleConfig, BundleCollection, RegisterBundles, et c).

Indeed a version is automatically assigned to the bundle:

<script src="/Scripts/Bundles/Foo?v=EjpuCsTAfNN9NMv5E8hER41p25Zj9w6ncqWRsYdqQUY1"></script>

My question is:
When does that version change? Can I rely on this? How does it work internally?

I might be wrong but one time I had to manually refresh the browser so that the script was updated, because the minor change I did to the script didn't took effect on the version.

What could have caused this?
Are minor changes considered in the versioning?

Answer 1

How does .net generates the version of bundle?

The version of bundle is a SHA256 based hash of all bundled content.

So if you will change any data of bundled files - version will be changed.