Clean Code Principles Every Developer Should Know

After three decades of writing and reviewing code, I’ve seen what separates maintainable codebases from those that become nightmares. The principles in Robert Martin’s “Clean Code” remain as relevant as ever. Here’s my take on the most impactful ones.

Meaningful Names

Names should reveal intent. A variable named d tells you nothing; daysSinceModification tells you everything.

// Bad
const d = 7;

// Good
const daysUntilDeadline = 7;

Functions Should Do One Thing

The Single Responsibility Principle applies to functions as much as classes. If a function is doing more than one thing, it should be split.

The Boy Scout Rule

“Always leave the code cleaner than you found it.” Small, incremental improvements add up to dramatically cleaner codebases over time.

Don’t Repeat Yourself (DRY)

Duplication is the root of many software evils. Every piece of knowledge should have a single, unambiguous, authoritative representation in a system.

Comment What, Not How

Comments should explain why code exists, not what it does. If you need to explain what the code does, it’s a sign the code isn’t clear enough.

// Bad: Explains the obvious
// Loop through users
for (const user of users) { ... }

// Good: Explains the why
// Process users in order to maintain audit trail consistency
for (const user of sortedByCreationDate(users)) { ... }

Conclusion

Clean code isn’t about perfection—it’s about writing code that your future self and teammates will thank you for. These principles are timeless because they’re rooted in human psychology and communication, not specific technologies.