Clean Names

Clean Names

N1: Choose Descriptive Names

Names should reveal intent. If a name requires a comment, it doesn't reveal its intent.

// Bad - what is d?
const d = 86400;

// Good - obvious meaning
const SECONDS_PER_DAY = 86400;

// Bad - what does this function do?
function proc(values: number[]) {
  return values.filter((value) => value > 0);
}

// Good - intent is clear
function filterPositiveNumbers(numbers: number[]) {
  return numbers.filter((number) => number > 0);
}

N2: Choose Names at the Appropriate Level of Abstraction

Don't pick names that communicate implementation; choose names that reflect the level of abstraction of the class or function.

// Bad - too implementation-specific
function getMapOfUserIdsToNames() {
  // ...
}

// Good - abstracts the data structure
function getUserDirectory() {
  // ...
}

N3: Use Standard Nomenclature Where Possible

Use terms from the domain, design patterns, or well-known conventions.

// Good - uses pattern name
class UserFactory {
  create(data: unknown) {
    // ...
  }
}

// Good - uses domain term
function calculateAmortization(principal: number, rate: number, term: number) {
  // ...
}

N4: Unambiguous Names

Choose names that make the workings of a function or variable unambiguous.

// Bad - ambiguous
function rename(source: string, target: string) {
  // ...
}

// Good - clear what's being renamed
function renameFile(oldPath: string, newPath: string) {
  // ...
}

N5: Use Longer Names for Longer Scopes

Short names are fine for tiny scopes. Longer scopes need longer, more descriptive names.

// Good - short name for tiny scope
const total = numbers.reduce((sum, n) => sum + n, 0);

// Good - longer name for module-level constant
const MAX_RETRY_ATTEMPTS_BEFORE_FAILURE = 5;

// Bad - short name at module level
const MAX = 5;

N6: Avoid Encodings

Don't encode type or scope information into names. Modern editors make this unnecessary.

// Bad - Hungarian notation
const strName = "Alice";
const arrUsers: string[] = [];
const nCount = 0;

// Good - clean names
const name = "Alice";
const users: string[] = [];
const count = 0;

// Bad - interface prefix
interface IUserRepository {
  findById(id: string): Promise<unknown>;
}

// Good - just name it
interface UserRepository {
  findById(id: string): Promise<unknown>;
}

N7: Names Should Describe Side Effects

If a function does something beyond what its name suggests, the name is misleading.

const configStore = new Map<string, string>();

// Bad - name doesn't mention file creation
function getConfig(configPath: string) {
  if (!configStore.has(configPath)) {
    configStore.set(configPath, "{}"); // Hidden side effect!
  }
  return JSON.parse(configStore.get(configPath) ?? "{}");
}

// Good - name reveals behavior
function getOrCreateConfig(configPath: string) {
  if (!configStore.has(configPath)) {
    configStore.set(configPath, "{}");
  }
  return JSON.parse(configStore.get(configPath) ?? "{}");
}

Quick Reference