High Performance Web Sites

Obfuscation

Obfuscation is an alternative optimization that can be applied to source code. Like minification, it removes comments and whitespace, but it also munges the code. As part of munging, function and variable names are converted into smaller strings making the code more compact, as well as harder to read. This is typically done to make it more difficult to reverse-engineer the code, but munging can help performance because it reduces the code size beyond what is achieved by minification.

Assuming that thwarting reverse-engineering is not your objective, the question arises about whether to minify or obfuscate. Minification is a safe, fairly straightforward process. Obfuscation, on the other hand, is more complex. There are three main drawbacks to obfuscating your JavaScript code:

Bugs

Because obfuscation is more complex, there's a higher probability of introducing errors into the code as a result of the obfuscation process itself.

Maintenance

Since obfuscators change JavaScript symbols, any symbols that should not be changed (for example, API functions) have to be tagged so that the obfuscator leaves them unaltered.

Debugging

Obfuscated code is more difficult to read. This makes debugging problems in your production environment more difficult.

Although I've never seen problems introduced from minification, I have seen bugs caused by obfuscation. Given the large amount of JavaScript maintained at Yahoo!, my guidelines recommend minification over obfuscation. The ultimate decision ...