I'm new to both .NET development and Umbraco due to recently starting a new role where I will be working heavily with both. As usual before starting development I am looking for some shortcut or helper functions that will enable me to work more productively. One set of helper functions I have found I have included below:

public static string DatedContent(this UrlHelper urlHelper, string contentPath)
{
  var datedPath = new StringBuilder(contentPath);
  datedPath.AppendFormat("{0}m={1}",
      contentPath.IndexOf('?') >= 0 ? '&' : '?',
      getModifiedDate(contentPath));
      return urlHelper.Content(datedPath.ToString());
}

private static string getModifiedDate(string contentPath)
{
    return System.IO.File.GetLastWriteTime(HostingEnvironment.MapPath(contentPath)).ToString("yyyyMMddhhmmss");
}

The functions above are called as follows:

<script src="@Url.DatedContent("~/scripts/product.js")"></script>

The aim of these functions is to automatically version Javascript and CSS files to ensure that the latest versions of each JavaScript and CSS file are pulled through by appending a modified date query string to the end of the file references.

My issue here is, and I apologise that this is such a newbie question, but where do I put this function in Umbraco 7 or is this functionality already supported?

From what I have learnt so far, content pages all have some base properties that include date created and date modified however CSS and Script files do not have these properties so I cannot simply reference these object properties using inline Razor code and condense them with the ToString method as I am doing the functions above.

My first thought was that these functions could be included at the top of the template where the razor code block is included automatically but as I am new to .Net I don't know if this is a standard convention.

Any help would be greatly appreciated.