It is one of the peephole optimizations that Closure Compiler performs to save some space (read: 2-3 characters) in the final output: http://code.google.com/p/c

It is one of the peephole optimizations that Closure Compiler performs to save some space (read: 2-3 characters) in the final output: http://code.google.com/p/closure-compiler/source/browse/src/com/google/javascript/jscomp/PeepholeSubstituteAlternateSyntax.java http://code.google.com/p/closure-compiler/source/browse/src/.... The compiler actually has a lot of cool little tricks like that to save space (since saving even a few bytes for a property like, say, Gmail, can translate to very large numbers very quickly)