I have use cases for virtualenv, but on my dev machine, to emulate a prod machine setup. But on a prod machine I will have to question hard every line in the in

I have use cases for virtualenv, but on my dev machine, to emulate a prod machine setup. But on a prod machine I will have to question hard every line in the install log, and virtualenv may not stay in. For JS, I don't think it's only problem is with browser compatibility, it also has other flaws and need some patching before being usable, I've heard.