:optimizations

The compiler will produce JS based on the optimization level:

• :none - multiple unminified files (fastest for development).
• :whitespace - single file w/ comments and whitespace removed
• :simple - single file w/ whitespace optimizations + minified local var names
• :advanced - single file w/ aggressive renaming, dead code removal, and inlining

:optimizations :none     ;; <-- recommended for development
:optimizations :advanced ;; <-- recommended for production
:optimizations :simple   ;; <-- recommended for Node

For a detailed explanation of the different optimization modes see Closure Compiler Compilation Levels