code-refactoring

Refactoring long TypeScript functions safely requires extracting methods into smaller helpers and validating behavior preservation via tests and static-analysis commands. A checklist-driven approach ensures functional equivalence before finalizing changes.

Removing code duplication involves consolidating repeated query and build logic using shared functions and parameter objects. This DRY approach reduces complexity and improves maintainability across the codebase.

Replacing conditional chains with polymorphism separates responsibilities and makes code easier to extend. This design improvement applies SOLID principles to restructure payment handling or similar logic structures.

Tests are required before refactoring to validate behavior preservation. A structured pre/post refactor checklist covers inputs, outputs, invariants, and dependencies to reduce regression risk during the process.

Creating a refactor plan requires breaking down complex code changes into small incremental steps. This approach enforces SOLID principles and introduces parameter objects while validating behavior at each stage.

Introduce parameter objects during refactoring to consolidate repeated query and build logic. This technique simplifies long functions and reduces duplication by grouping related parameters together.