Benefit of compressing javascript/css files when using IIS httpCompression

Question

It looks like IIS httpCompression compresses your files. If this compression is in place, what is the reason to compress files using compression tools like: Packer, JSMin or Yahoo Compressor?

Answer 1

The tools you mention are minifiers, and not compression.

Try "zipping" your normal and your minified javascript files and see what size they both are afterwards. You may find it is smaller, you may find it makes no difference.

The one gain you will get though is that browsers of proxies that don't support compression will still benefit from minification.

Answer 2

the reason is, or was, that some browsers didn't support gzip'ed HTTP transfer or had bugs with it. We're talking NS4 and early IE here so the reasons aren't really there anymore unless you have no control over your webserver (3rd-party hosting).