Naming Conventions: Write Self-Documenting Code

// Bad
const d = new Date();  // What does d mean?

// Good
const currentDate = new Date();

// Bad
const d = days;  // Time since when?
const t = time;  // What time?

// Good
const daysSinceCreation = days;
const elapsedTimeInSeconds = time;

// Bad - misleading
const userList = [];  // But it contains User objects
const userNames = [];  // Contains full user objects

// Good
const users = [];
const names = [];

// Bad - noise words
const userData = {};
const userInfo = {};  // What's the difference?

// Good
const userRecord = {};
const userPreferences = {};

// Booleans - prefixes
const isActive = true;
const hasPermission = false;
const canEdit = true;
const shouldUpdate = true;

// Collections - plural
const users = [];
const userMap = new Map();
const userSet = new Set();

// Verbs for actions
function getUser(id: string) { }
function createUser(data: User) { }
function updateUser(id: string, data: User) { }
function deleteUser(id: string) { }

// Return booleans - is/has/can
function isValid() { }
function hasPermission(user: User) { }
function canEdit(user: User) { }

// Nouns
class UserService { }
class OrderProcessor { }
class EmailValidator { }

// UPPER_SNAKE_CASE
const MAX_RETRIES = 3;
const DEFAULT_TIMEOUT = 5000;
const API_BASE_URL = 'https://api.example.com';

// i, j fine for loops
for (let i = 0; i < 10; i++) {
  for (let j = 0; j < 10; j++) {
    // Short scope, short names OK
  }
}

// Full words for larger scope
let retryCount = 0;
let maxRetries = 3;

// Not
let r = 0;
let m = 3;

// Use business terminology
class ShoppingCart { }  // Not Cart or Basket
class OrderProcessor { }  // Not Processor
class PriceCalculator { }  // Not Calculator

// What does this do?
const p = u.permissions.includes('edit');

const hasEditPermission = user.permissions.includes('edit');

class User {
  canEdit() {
    return this.permissions.includes('edit');
  }
}

if (user.canEdit()) { }