General Closure Compiler Debugging Tips

• Use the VERBOSE warning level. This turns on all of the checks.
• Use the debug flag. It makes renamed symbols ridiculously long, but they are named in such a way you can find the original. If code works with the debug flag but not without it, it is almost certainly a renaming issue.
• Definitely use formatting=PRETTY_PRINT. Debugging compacted code is painful without it.
• Use source maps

General Closure Compiler Debugging Tips

• Use the VERBOSE warning level. This turns on all of the checks.
• Use the debug flag. It makes renamed symbols ridiculously long, but they are named in such a way you can find the original. If code works with the debug flag but not without it, it is almost certainly a renaming issue.
• Definitely use formatting=PRETTY_PRINT. Debugging compacted code is painful without it.
• Use source maps
• Disable the type based optimizations with --use_types_for_optimization false. Incorrect type annotations can cause the compiler to make invalid assumptions.

UPDATE: As of the 20150315 compiler release, the type based optimizations are enabled by default.

General Closure Compiler Debugging Tips

• Use the VERBOSE warning level. This turns on all of the checks.
• Use the debug flag. It makes renamed symbols ridiculously long, but they are named in such a way you can find the original. If code works with the debug flag but not without it, it is almost certainly a renaming issue.
• Definitely use formatting=PRETTY_PRINT. Debugging compacted code is painful without it.

General Closure Compiler Debugging Tips

• Use the VERBOSE warning level. This turns on all of the checks.
• Use the debug flag. It makes renamed symbols ridiculously long, but they are named in such a way you can find the original. If code works with the debug flag but not without it, it is almost certainly a renaming issue.
• Definitely use formatting=PRETTY_PRINT. Debugging compacted code is painful without it.
• Use source maps

General Closure Compiler Debugging Tips

• Use the VERBOSE warning level. This turns on all of the checks.
• Use the debug flag. It makes renamed symbols ridiculously long, but they are named in such a way you can find the original.
• Definitely use formatting=PRETTY_PRINT. Debugging compacted code is painful without it.

General Closure Compiler Debugging Tips

• Use the VERBOSE warning level. This turns on all of the checks.
• Use the debug flag. It makes renamed symbols ridiculously long, but they are named in such a way you can find the original. If code works with the debug flag but not without it, it is almost certainly a renaming issue.
• Definitely use formatting=PRETTY_PRINT. Debugging compacted code is painful without it.