You do not need to use the library to use the compiler which is great, I first came across the closure compiler when I had finished Nina’s Workshop Drop and needed a way to compile all the scripts. I looked into various solutions but Closure seemed to offer the best features.
Developed within Googles 20% Time (like Gmail), supposedly it was named “Closure” because it was going to bring closure to a period of time at Google where they had no unified tools (I think I heard this on a podcast).
myJSON.myNestedObject myJSON[ "myNestedObject"]
You can find out a lot more on the Google Closure site: https://developers.google.com/closure/library/docs/tutorial
Finally here’s a talk was given by one of the Google developers when they had just release Closure into the public back in 2011.