ASP.NET Bundling and Minification - Including Already Minified Files for Production Bundles and Unminified Files for Development

Question

I want some expert advice on ASP.NET MVC Bundling and Minification. I have in my project script files that have both unminified (.js) and minified versions (.min.js). I have included them in my script bundle as follows:

bundles.Add(new ScriptBundle("~/bundles/layout").Include(
                    "~/Scripts/jquery-{version}.js",
                    "~/Scripts/lib/errorhandling.js",
                    "~/Scripts/lib/errorhandling.min.js",
                    "~/Scripts/vendor/modernizr.custom.js",
                    "~/Scripts/vendor/modernizr.custom.min.js",
                    "~/Scripts/toastr.js",
                    "~/Scripts/toastr.min.js"));

It seems that the bundle indeed contains only once each script file, not twice. I have confirmed this both for development and production. (As a side note, in development, that is, when debug=true, the bundles are not rendered but the files are included as separate script tags. This is the desired behaviour for me, as well.)

My questions are:

(1) Is this the best and recommended way to include already minified files for production setup and unminified files for development?

(2) Does ASP.NET try to minify the whole bundle in production (even though it is already minified)? If yes, what is the best way to prevent ASP.NET from trying to minify the bundle?

Thanks in advance!

Answer 1

There is no need to specifically include the minified versions in your script bundle. By default, MVC will search for a matching file with .min.js and include that (not entirely sure if it trys to minify further). If not, it creates a minified version. You can test this by adding the following to BundleConfig.cs

using System.Web.Optimization;

then adding the following at the end to override debug=true in development

BundleTable.EnableOptimizations = true;

From MS documentation

The bundling framework follows several common conventions such as:

• Selecting “.min” file for release when “FileX.min.js” and “FileX.js” exist.
• Selecting the non “.min” version for debug.
• Ignoring “-vsdoc” files (such as jquery-1.7.1-vsdoc.js), which are used only by IntelliSense.