Code Smells

Summary of what I learned from JumpStart’s clean code session.

For more on how to write clean code, you can refer to: “Refactoring: Improving the Design of Existing Code” by Martin Fowler.

1. Mysterious Names

When: Names are not self-explanatory and descriptive.

Solution: Use clear, descriptive names.

2. Bad comments

When: Methods filled with explanatory comments that are unnecessary.

Solution: Code should strive to be self-explanatory. Comment the pitfalls and not the obvious.

3. Complex conditions

When: There are long expressions that are hard to read.

Solution: Simplify with De Morgan’s Law.

4. Don’t use “else” when unnecessary

When: Code looks like a Christmas Tree.

Solution: Early returns.

5. Double negatives

Why: Double negatives are difficult to read.

6. Loopy code

Solution: Use .map, .filter, .reduce instead.

7. Duplicate code

Solution: Refactor out common functions.

8. Dead code

When: Code that is not used because it’s obsolete.

Solution: Remove greyed out code.

9. Overly long function

When: Methods are more than 10 lines.

Solution: Follow the single responsibility principle.

10. Long parameter lists

Solution: Extract into class methods.

11. God class

When: Class has too many fields, methods or/and lines of code.

12. Speculative Generality

When: Unused code for “what ifs”.

Solution: If in doubt, YAGNI (You probably Aren’t Gonna Need It).

13. Primitive Obsession

When: A lot of primitives instead of objects. (Eg: admin_role = 1)

Solution: Wrap primitives in classes.

Resources:

https://blog.codinghorror.com/code-smells/
https://refactoring.guru/refactoring/smells
https://williamdurand.fr/2013/06/03/object-calisthenics
https://hackernoon.com/lessons-learned-common-react-code-smells-and-how-to-avoid-them-f253eb9696a4
https://github.com/Droogans/unmaintainable-code