Purpose

Run build, type checking, and linting to ensure code quality before committing or deploying.

Commands

1. Development

bash

# Start development server
npm run dev

# Development server runs on http://localhost:3000
# Hot reload enabled

2. Type Checking

bash

# Type check with TypeScript compiler
npx tsc --noEmit

# Shows all TypeScript errors without emitting files

3. Linting

bash

# Check code with Biome
npm run lint

# Auto-fix issues
npm run format

4. Production Build

bash

# Build for production
npm run build

# Build output goes to .next/ directory
# This command:
# - Compiles TypeScript
# - Optimizes React components
# - Generates static pages
# - Bundles JavaScript/CSS

5. Start Production Server

bash

# Start production server (after build)
npm start

Common Issues and Fixes

TypeScript Errors

bash

# Check specific file
npx tsc --noEmit src/app/page.tsx

# Common fixes:
# - Add missing types
# - Check import paths (@/ alias)
# - Verify interface implementations

Build Failures

bash

# Clean cache and rebuild
rm -rf .next node_modules/.cache
npm run build

# Check for:
# - Missing dependencies
# - Import cycles
# - Server/client component issues

Linting Errors

bash

# Show all issues
npm run lint

# Auto-fix formatting
npm run format

# Common Biome rules:
# - No unused variables
# - Consistent quotes
# - Proper spacing

Pre-Commit Checklist

Run these commands before committing:

bash

# 1. Format code
npm run format

# 2. Check linting
npm run lint

# 3. Type check
npx tsc --noEmit

# 4. Build to catch production issues
npm run build

# If all pass, you're good to commit!

CI/CD Integration

For GitHub Actions or similar:

yaml

- name: Install dependencies
  run: npm ci

- name: Lint
  run: npm run lint

- name: Type check
  run: npx tsc --noEmit

- name: Build
  run: npm run build

Performance Tips

bash

# Analyze bundle size
npm run build
# Check .next/analyze output

# Check for:
# - Large dependencies
# - Duplicate packages
# - Unnecessary imports

Database Migrations Before Build

If you have pending migrations:

bash

# Initialize schema
npm run init:schema

# Run specific migration
npm run migrate:auth

# Check database
npm run check:db

Environment Variables

Required for build:

bash

# .env.local
DATABASE_URL=data/learning-cards.db
NEXTAUTH_SECRET=your-secret-here
NEXTAUTH_URL=http://localhost:3000

# For production:
NODE_ENV=production

Troubleshooting

"Module not found" errors

bash

# Verify paths in tsconfig.json
# Check @/ alias points to ./src/*

# Restart dev server
npm run dev

"Cannot find module" in production

bash

# Ensure all imports use correct casing
# Check that files exist in production build

Out of memory during build

bash

# Increase Node memory
NODE_OPTIONS=--max-old-space-size=4096 npm run build

Best Practices

•✅ Run type check before committing
•✅ Fix all linting errors
•✅ Test production build locally
•✅ Check bundle size after changes
•✅ Keep dependencies updated
•⚠️ Don't commit with build errors
•⚠️ Don't ignore TypeScript errors
•⚠️ Don't skip linting