WordPress is shipped with a current jQuery version by default. When you update your WordPress core and there’s a new version of the jQuery library that is used in the package, it will be updated, too. But you might have reasons not to update your WordPress core, want to use an outdated version of jQuery, or use the jQuery library hosted on a content distribution network (CDN). Google is hosting jQuery and other libraries publicly that you could use and include in your WordPress theme.
I am glad that I have set up multiple environments for a current project that I’m working on. The live site, a testing site, and two developing sites – all with their unique databases just in case something’s going very Murphy – are a fair deal to develop and test new features and bugfixes on any web project. But there’s one major drawback: Keeping data “in sync”. Version control like git or SVN do a great job with all that PHPs,