Node Auto Debugger

Scan Node.js/Express/Next.js projects for bugs, security issues, and anti-patterns. Use when debugging a Node.js web app, running code audits, fixing client-side exceptions, hydration errors, hardcoded secrets, missing error handling, or preparing for production. Covers backend (Express/Fastify routes, async errors, undefined vars) and frontend (Next.js/React hydration, SSR crashes, wagmi/RainbowKit issues, missing 'use client' directives) plus config validation and optional build verification.

Node.js Auto Debugger

Automated scanner for Node.js projects — finds bugs across backend, frontend, and config.

Quick Start

node scripts/auto-debug.js <project-dir>

Options:

• --build — Also run npm run build and capture compilation errors

What It Checks

Backend (Express/Fastify)

• Undefined variables — .push() on undeclared variables
• Missing try/catch — async route handlers without error handling
• Hardcoded secrets — API keys, private keys, passwords in source

Frontend (Next.js/React)

• Missing 'use client' — hooks or browser APIs without directive
• Hydration risks — Date.now(), Math.random() in render (should be in useEffect or useState)
• SSR crashes — window/document access outside useEffect
• Missing loading states — wagmi hooks without isLoading/isFetching

Config

• Missing next.config.js — defaults warning
• Missing build script — package.json validation

Output

Report saved to <project>/AUTO-DEBUG-REPORT.md with issues grouped by severity:

• 🔴 Critical — will crash or leak secrets
• 🟠 High — likely runtime errors
• 🟡 Medium — hydration mismatches, missing loading states
• 🟢 Low — minor issues

Exit code: 1 if any critical issues found, 0 otherwise.

Fixing Hydration Issues (Next.js)

Date.now()/new Date() in render:

// ❌ Bad — causes hydration mismatch
const now = Math.floor(Date.now() / 1000);

// ✅ Good — guard with isMounted
const [isMounted, setIsMounted] = useState(false);
useEffect(() => { setIsMounted(true); }, []);
const now = isMounted ? Math.floor(Date.now() / 1000) : 0;

Math.random() in render:

// ❌ Bad — different on server vs client
<div style={{ left: `${Math.random() * 100}%` }} />

// ✅ Good — pre-generate in useState (runs once)
const [particles] = useState(() =>
  Array.from({ length: 10 }, () => ({
    left: `${Math.random() * 100}%`,
  }))
);

window/document access:

// ❌ Bad — crashes during SSR
const width = window.innerWidth;

// ✅ Good — only after mount
const [width, setWidth] = useState(0);
useEffect(() => setWidth(window.innerWidth), []);