Write Comments

Commenting

When to Comment

Code should be self-explanatory through good naming. Comments add value only when they explain why something is done — not what it does.

Comment when:

• Explaining non-obvious intent or business logic
• Documenting known edge cases or external constraints
• Noting a workaround with a link to the upstream issue

Don't comment when:

• The code is clear from reading it
• You're narrating what the code obviously does

How to Comment

Good Comments

// Delay is intentional: the third-party API enforces a 1s rate limit per key
await delay(1000);

// Uses linear search because this list is always < 10 items and never hot
const found = items.find((item) => item.id === targetId);

Bad Comments

// Increment counter
counter++;

// Call the API
const result = await fetchData();

// Return the value
return value;

Anti-Patterns

Obvious Comments

// Bad: restates what the code already says
const user = getUser(id); // Get the user by id

Redundant JSDoc

Avoid JSDoc on private functions or functions whose signature is self-documenting.

// Bad: JSDoc that adds nothing
/**
 * Gets the user.
 * @param id - The user id.
 * @returns The user.
 */
function getUser(id: string): User { ... }

// Good: JSDoc only when it adds non-obvious context
/**
 * Returns the user record, or throws `UserNotFoundError` if the id is
 * not present in the active-users projection. Does NOT check the archive.
 */
function getUser(id: string): User { ... }

TODO Comments

Don't leave TODO comments to bypass lint rules or defer real fixes.

// Bad: silences a rule without explanation
// eslint-disable-next-line @typescript-eslint/no-explicit-any
function process(data: any) { ... }

// Good: fix the underlying issue instead
function process(data: unknown) { ... }

If a TODO is genuinely needed (tracked work), include a ticket reference:

// TODO(#1234): remove once the upstream API supports batch deletes

Divider Comments

// Bad: dash dividers
// ---------------------------------------------------------------------------
// Configuration
// ---------------------------------------------------------------------------

// Bad: equals dividers
// ===========================
// Configuration
// ===========================

// Bad: plain section label with no emoji
// Configuration

// Bad: #region blocks
//#region 🔧 Configuration
//#endregion

Use emoji section comments instead — see Section Comments below.

Section Comments

When a file benefits from logical groupings, mark each section with a single-line emoji comment.

Format

// <emoji> <Section name>

• Emoji first — conveys purpose at a glance
• Capital first letter — // 🔧 Configuration, not // 🔧 configuration
• Single line — no closing marker, no surrounding dash lines
• Python uses # instead of // — same rules otherwise

Examples

TypeScript / JavaScript

// 🔧 Configuration

const MAX_RETRIES = 3;
const API_TIMEOUT = 5_000;

// 🎭 Mocks

vi.mock("./api.js");

// 🧪 Tests

describe("MyService", () => { ... });

NestJS service layout

@Injectable()
export class MyService {
  // 🏗 Dependency injection
  constructor(private readonly logger: LoggerService) {}

  // 🔐 Private fields

  // 🔑 Public fields

  // 🔏 Private methods

  // 🌎 Public methods
}

Python

# 🔧 Configuration

MAX_RETRIES = 3

# 🧪 Tests

class TestMyService(unittest.TestCase): ...

Emoji Reference

Rules Summary

1. Format: // <emoji> <Section name> (TypeScript/JS) or # <emoji> <Section name> (Python)
2. Section name: capitalized first letter, short noun phrase
3. Never wrap a section comment in dash lines or any other delimiter
4. Never use #region/#endregion — plain emoji comments are sufficient
5. Choose an emoji that conveys the section's purpose; consult the table above