coding-practices

name	coding-practices
description	Code quality: error handling, validation, logging, DRY, and self-documenting code. Use when writing or reviewing code quality, handling errors, or validating inputs. Do NOT use for language-specific syntax (use javascript-practices or go-practices).

Coding Practices

Guidelines for writing maintainable, robust, and self-documenting code.

Quick Start

// Self-documenting with proper error handling
function createUser(email: string, age: number): User {
  if (!email.includes("@")) throw new Error("Invalid email");
  if (age < 0 || age > 150) throw new Error("Invalid age");
  return { email, age };
}

Key Principles

• Compare entities by IDs, never by slugs/usernames/strings
• Use meaningful names (self-documenting code)
• Comments explain "why", not "what"
• DRY: abstract when used 3+ times
• Validate all input data
• Handle all error cases with proper Error objects
• Never ignore errors — handle or propagate with context
• Use named constants instead of magic values
• Explicit checks only — never use truthy/falsy for non-booleans
• Early returns to reduce nesting (guard clauses first)

Anti-Patterns

"I'll add a quick if (!value) check" No. Use explicit comparisons: value === null, value === undefined, str === "".

"I'll just throw new Error('failed')" No. Include context: domain-specific error types, { cause: error }, correlation IDs.

References

See rules.md for complete guidelines with examples.