Home/ Questions/Q 7015675
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-05-27T22:40:59+00:00

I’m trying to enable gzip compression on a site on our work intranet. Unfortunately,

  • 0

I’m trying to enable gzip compression on a site on our work intranet. Unfortunately, I don’t have access to IIS, so any changes I make have been through web.config.

The server is running IIS 6 and .NET 2.0.

I enabled compression by adding an httpmodule

public class EnableCompression : IHttpModule
{
    public void Init(HttpApplication application)
    {
        application.BeginRequest += 
            (new EventHandler(this.Application_BeginRequest));

    }

    private void Application_BeginRequest(Object source, EventArgs e)
    {
        HttpContext context = HttpContext.Current;
        context.Response.Filter = new GZipStream(context.Response.Filter, CompressionMode.Compress);
        HttpContext.Current.Response.AppendHeader("Content-encoding", "gzip");
        HttpContext.Current.Response.Cache.VaryByHeaders["Accept-encoding"] = true;
    }

}

I registered in the web.config…

<system.web>
    <httpModules>
      <add name="EnableCompression" type="EnableCompression"/>
    </httpModules>
</system.web>

Well, the above worked fine, except javascript and css files do not get compressed. From what I have found, I would have to add .js and .css to the application mappings in IIS 6, but of course I can’t do that.

Apparently this can be done via the web.config file, but I don’t know how to do that.

How can I enable compression for .js and .css files?

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    In IIS6, static code is not processed by managed HttpModules; it requires a native ISAPI.

    One trick you can use is to convert your *.js and *.css files into dynamic files. You do this by changing them to be *.aspx, and set the ContentType to the right MIME type. For example:

    this.Response.ContentType = "application/x-javascript";

    The only other trick is to set StyleSheetTheme="" in the Page directive in the markup file. Otherwise, the runtime will insist on a <head> section in the document. You can enable output caching to minimize the performance impact.

    I wrote a blog post about this on the JS side, in case it helps (CSS is similar, just with a different MIME type): http://www.12titans.net/p/dynamic-javascript.aspx

    Unfortunately, this requires changing the name of your JS and CSS files in your app, but if you want compression and don’t have access to IIS, I don’t think there’s a way around that.

    If you want to keep the *.js and *.css extensions, you can do so by adding a handler for them in your web.config. For example:

    <compilation>
  <buildProviders>
    <add extension=".css" type="System.Web.Compilation.PageBuildProvider"/>
  </buildProviders>
</compilation>

<httpHandlers>
  <add path="*.css" verb="*" type="System.Web.UI.PageHandlerFactory"
       validate="true"/>
</httpHandlers>

    This helps from a naming perspective, but not performance; the files will still be dynamic — they are basically *.aspx files, but with a different extension. It also doesn’t work correctly with ASP.NET Themes, since pages in the Themes folder can’t be dynamic, regardless of their extension.

    • 0