refactoring-patterns

| Long method (>20 lines) | Extract Method | | Large class | Extract Class | | Long parameter list (>3) | Introduce Parameter Object | | Duplicated code | Extract Method/Class | | Complex conditional | Decompose Conditional | | Magic numbers | Named Constants | | Nested loops | Replace Loop with Pipeline |

| Extract Method | 50-line function | 5 small functions | | Extract Class | Class doing 5 things | 5 single-purpose classes | | Parameter Object | fn(a,b,c,d,e,f) | fn(options) | | Replace Conditional | if (type === 'a') {...} | Polymorphism | | Pipeline | Nested loops | .filter().map().reduce() |

| Without tests | No safety net | Write tests first | | Big bang | Rewrite everything | Small incremental steps | | For perfection | Endless tweaking | Good enough, move on | | Premature abstraction | Pattern not clear yet | Wait for Rule of Three | | During feature work | Mixed changes | Separate commits |