Meaningful variable names

Good names explain what something is without needing a comment. Use full words, name booleans like questions (isLoading, hasError), and name functions with verbs (getUser, calculateTotal).

// Bad
const d = 7
const arr = getStuff()
function calc(a, b) { return a * b }
let flag = false

// Good
const daysUntilDeadline = 7
const activeUsers = getActiveUsers()
function calculateTotal(price, quantity) { return price * quantity }
let isLoading = false