VS can merge output into one file, but it cannot for example to minimize it. For minification or any other further processing you have to run other external tools. If you want to do all this from VS, you can set commands into post-build events. For example take VS output and pass it into minification program (uglify in screenshot).  While settings for output can be different for Debug and Release and setting is separated, there are no separate build events for Debug and Release. Your build