Coding Standards

Standards for JavaScript/TypeScript applicable across this project and future work.

When to Apply

• •Writing new code or modifying existing modules
• •Reviewing PRs or doing self-review
• •Refactoring or adding features

Principles

• •Readability first: Clear names, small functions, consistent style
• •KISS: Simplest solution that works; avoid over-engineering
• •DRY: Extract repeated logic into functions or shared modules
• •YAGNI: Don’t add features or abstraction until needed

Naming

• •Variables: Descriptive, not single letters (e.g. cartItems, isLoading)
• •Functions: Verb-noun (e.g. fetchProduct, validateCheckout, formatPrice)
• •Booleans: is, has, should prefix (e.g. isValid, hasDiscount)
• •Constants: UPPER_SNAKE for true constants; camelCase for config objects

Immutability (Critical)

• •Do not mutate existing objects or arrays in place
• •Prefer spread and new arrays:

// Good
const updated = { ...user, name: newName }
const next = [...items, newItem]
const filtered = items.filter(...)

// Bad
user.name = newName
items.push(newItem)

Functions and Files

• •Functions: small and focused; under ~50 lines when practical
• •Files: single responsibility; under ~400 lines typical, ~800 max
• •Organize by feature/domain (e.g. cart, product, checkout) rather than only by type (all "utils")

Error Handling

• •Handle errors explicitly; never swallow them
• •User-facing: short, clear messages; server/logs: full context
• •Async: use try/catch with async/await; consider Promise.all for independent work
• •Validate at boundaries (input, API responses); fail fast with clear errors

Input and Validation

• •Validate all external input (forms, query params, API payloads)
• •Use schema-based validation (e.g. Zod) when available
• •No hardcoded secrets; use env vars or config

Code Quality Checklist

Before considering work complete:

• • Names are clear and consistent
• • Functions are small and focused
• • No unnecessary mutation
• • Errors handled and logged appropriately
• • No console.log left in production paths
• • No hardcoded secrets or sensitive data