I have inherited a web application to maintain. The application entails hundreds of thousands of lines of Javascript across hundreds of libraries that get loaded/unloaded at run time. I need to add a feature to the site to let a user know if his/her browser doesn't support the minimum Javascript version required to run the site, which, in turn, requires me to analyze all the Javascript in the site in order to know the minimum required version. The libraries were written/added as-needed over the years, using whatever features Javascript supported at the time, so some libraries can work with older Javascript than others.
What offline software or utility can I use to analyze all the Javascript in the project and determine the minimum Javascript version that is found? By "offline" I mean not uploading the project to a web-based analyzer or otherwise transferring any part of the project to a third party for analyzation. An open source tool would be preferred, but I would pay for a commercial tool out-of-pocket if absolutely necessary and not more than $100.