reverse-engineer-js

reverse-engineer-js is a skill for Claude Code, Codex from vladmdgolam/agent-skills. It costs 146 tokens per session (2,261 once invoked), scanned A, original, MIT.

A workflow for making minified or deliberately obscured JavaScript easier to read by recovering meaningful names, formatting code, and unpacking bundled modules. A source map, when available, can restore the original source more directly.

In plain words
What is it for?
Use it to inspect JavaScript bundles, check for source maps, format single-file code, split webpack or Browserify modules, and rename unclear variables and functions.
Why use it?
Compressed bundles are difficult to inspect and debug because names and module boundaries may be hidden. This workflow helps developers investigate the code while checking for existing source information first.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: mentions Claude Code.

Good fit Use it to inspect JavaScript bundles, check for source maps, format single-file code, split webpack or Browserify modules, and rename unclear variables and functions.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/vladmdgolam/agent-skills/reverse-engineer-js
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add vladmdgolam/agent-skills --skill reverse-engineer-js
Clone the repo
git clone --depth 1 https://github.com/vladmdgolam/agent-skills

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for reverse-engineer-js

README.md
[![agentmods](https://agentmods.dev/badge/skills/vladmdgolam/agent-skills/reverse-engineer-js/github.svg)](https://agentmods.dev/skills/vladmdgolam/agent-skills/reverse-engineer-js)
Your own site
<a href="https://agentmods.dev/skills/vladmdgolam/agent-skills/reverse-engineer-js"><img src="https://agentmods.dev/badge/skills/vladmdgolam/agent-skills/reverse-engineer-js/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for reverse-engineer-js

Your own site · 80×15
<a href="https://agentmods.dev/skills/vladmdgolam/agent-skills/reverse-engineer-js"><img src="https://agentmods.dev/badge/skills/vladmdgolam/agent-skills/reverse-engineer-js.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 146 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,261 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 16 findings, up to high

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • high Excessive Agency · line 26
    Skill selects an external model or provider that may use a different account or billing plan than the operator expects. Undisclosed model switches can cause unexpected cost or quota consumption.
    Fix: Remove the model/provider override or disclose it prominently and require explicit operator approval before invoking an external coding CLI or billed model.
  • high Excessive Agency · line 35
    Skill selects an external model or provider that may use a different account or billing plan than the operator expects. Undisclosed model switches can cause unexpected cost or quota consumption.
    Fix: Remove the model/provider override or disclose it prominently and require explicit operator approval before invoking an external coding CLI or billed model.
  • high Excessive Agency · line 50
    Skill selects an external model or provider that may use a different account or billing plan than the operator expects. Undisclosed model switches can cause unexpected cost or quota consumption.
    Fix: Remove the model/provider override or disclose it prominently and require explicit operator approval before invoking an external coding CLI or billed model.
  • high Excessive Agency · line 120
    Skill selects an external model or provider that may use a different account or billing plan than the operator expects. Undisclosed model switches can cause unexpected cost or quota consumption.
    Fix: Remove the model/provider override or disclose it prominently and require explicit operator approval before invoking an external coding CLI or billed model.
  • high Tool Misuse · line 161
    Tool parameters are crafted to achieve unintended or unsafe behavior. Parameter abuse can bypass intended safety checks (e.g. shell=True, --force, dangerous glob patterns).
    Fix: Validate all tool parameters against an allowlist. Reject dangerous parameter values (shell=True, --force, -rf /) and use safe defaults.
  • medium MCP Rug Pull · line 26
    npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.
    Fix: Pin the version: npx @scope/[email protected]
  • medium MCP Rug Pull · line 35
    npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.
    Fix: Pin the version: npx @scope/[email protected]
  • medium MCP Rug Pull · line 38
    npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.
    Fix: Pin the version: npx @scope/[email protected]
  • medium MCP Rug Pull · line 50
    npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.
    Fix: Pin the version: npx @scope/[email protected]
  • medium MCP Rug Pull · line 77
    npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.
    Fix: Pin the version: npx @scope/[email protected]
  • medium MCP Rug Pull · line 92
    npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.
    Fix: Pin the version: npx @scope/[email protected]
  • medium MCP Rug Pull · line 105
    npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.
    Fix: Pin the version: npx @scope/[email protected]
  • medium MCP Rug Pull · line 120
    npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.
    Fix: Pin the version: npx @scope/[email protected]
  • medium MCP Rug Pull · line 149
    npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.
    Fix: Pin the version: npx @scope/[email protected]
  • medium MCP Rug Pull · line 103
    npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.
    Fix: Pin the version: npx @scope/[email protected]
  • medium MCP Rug Pull · line 121
    npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.
    Fix: Pin the version: npx @scope/[email protected]
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00146 $0.02261
Opus 5 $0.00073 $0.01130
Sonnet 5 $0.00029 $0.00452
Haiku 4.5 $0.00015 $0.00226

Measured yesterday against content hash 79ccb6dc681e, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

reverse-engineer-js scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/reverse-engineer-js/SKILL.md · 162 lines

How it starts

The opening of the file, as written. The whole thing — 162 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Reverse Engineer JS

LLM-assisted deobfuscation of minified / mangled JavaScript using humanifyjs plus surrounding tooling for extracting and reintegrating modules.

Tools at a glance

Tool Purpose When
humanifyjs (npx) Rename mangled vars/functions via LLM Mangled but already valid JS
prettier / js-beautify Reformat single-line minified code Before humanify, if needed
webcrack Unpack webpack / browserify bundles into per-module files When bundle is one big file
Source-map sleuthing // # sourceMappingURL=... may exist next to the bundle Always check first — beats LLM rename

Always check for a sourcemap (bundle.js.map or sourceMappingURL comment in the file) before spending tokens on humanify. If found, original sources are recoverable for free.

Default humanify invocation

Use Gemini unless the user says otherwise:

npx humanifyjs gemini -m "gemini-3.8-flash" -o <outputDir> <inputFile>

Requires GEMINI_API_KEY in env (the project's root .env is the usual place).

Other backends:

# OpenAI
npx humanifyjs openai --apiKey="$OPENAI_API_KEY" --model gpt-4.1-mini bundle.js

# Local (slower, free)
npx humanifyjs local bundle.js

Critical gotchas

1. Pseudo-TTY required in non-interactive shells

humanify calls process.stdout.cursorTo(...) for its progress bar. In Claude Code / CI / piped contexts, stdout is not a TTY and the call crashes with TypeError: process.stdout.cursorTo is not a function.

Wrap the call in script -q /dev/null:

script -q /dev/null npx humanifyjs gemini -m "gemini-3.8-flash" -o "$OUT" "$IN"

(macOS/BSD script syntax. On Linux: script -qc "<cmd>" /dev/null.)

2. Output filename is fixed

humanify always writes its result as <outputDir>/deobfuscated.js regardless of input filename. Don't expect module_1234.js in → module_1234.js out.

3. Long files = long runs

Read the full file on GitHub · 162 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday Changed · -2 tokens per session 79ccb6dc681e
  2. 10d ago First seen · 162 lines · 148 tokens per session scan A 1519783c3fe2

Subscribe to this mod's changes

reverse-engineer-js is a skill published in the GitHub repository vladmdgolam/agent-skills (8 stars, last pushed yesterday), licensed MIT. It adds 146 tokens to every session and 2,261 once invoked, about $0.0007 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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