Vercel Composition Patterns
supabase/supabase
React composition patterns that scale. An agent skill from supabase/supabase.
A skill your agent uses when reviewing code the JS engine (SpiderMonkey, js/src/) or self-reviewing code while producing it.
Install JS Review
$ npx skills add mozilla-firefox/firefox --skill js-review -a claude-codeProject install by default; add -g for ~/.claude/skills/.
$ gh skill install mozilla-firefox/firefox js-review --agent claude-codeProject scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).
$ git clone --depth 1 https://github.com/mozilla-firefox/firefox.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.agents/skills/js-review .claude/skills/js-review && rm -rf skills-srcUse ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.
Claude Code skills documentation · loads skills from .claude/skills/
Install the "js-review" agent skill from https://github.com/mozilla-firefox/firefox/tree/main/.agents/skills/js-review into .claude/skills/js-review/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "js-review", then confirm the skill loads.Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$skill-installer install https://github.com/mozilla-firefox/firefox/tree/main/.agents/skills/js-reviewType this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.
$ npx skills add mozilla-firefox/firefox --skill js-review -a codexProject install goes to .agents/skills/; add -g for ~/.codex/skills/.
$ gh skill install mozilla-firefox/firefox js-review --agent codexProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/mozilla-firefox/firefox.git skills-src && mkdir -p .agents/skills && cp -r skills-src/.agents/skills/js-review .agents/skills/js-review && rm -rf skills-srcUse ~/.agents/skills/ instead of .agents/skills for a personal install.
Codex skills documentation · loads skills from .agents/skills/
Install the "js-review" agent skill from https://github.com/mozilla-firefox/firefox/tree/main/.agents/skills/js-review into .agents/skills/js-review/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "js-review", then confirm the skill loads.Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add mozilla-firefox/firefox --skill js-review -a cursorProject install goes to .agents/skills/; add -g for ~/.cursor/skills/.
$ gh skill install mozilla-firefox/firefox js-review --agent cursorProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/mozilla-firefox/firefox.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/.agents/skills/js-review .cursor/skills/js-review && rm -rf skills-srcUse ~/.cursor/skills/ instead of .cursor/skills for a personal install.
Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/
Install the "js-review" agent skill from https://github.com/mozilla-firefox/firefox/tree/main/.agents/skills/js-review into .cursor/skills/js-review/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "js-review", then confirm the skill loads.Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gemini skills install https://github.com/mozilla-firefox/firefox.git --path .agents/skills/js-review--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.
$ npx skills add mozilla-firefox/firefox --skill js-review -a gemini-cliProject install goes to .agents/skills/; add -g for ~/.gemini/skills/.
$ gh skill install mozilla-firefox/firefox js-review --agent gemini-cliProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/mozilla-firefox/firefox.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/.agents/skills/js-review .gemini/skills/js-review && rm -rf skills-srcUse ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.
Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/
Install the "js-review" agent skill from https://github.com/mozilla-firefox/firefox/tree/main/.agents/skills/js-review into .gemini/skills/js-review/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "js-review", then confirm the skill loads.Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gh skill install mozilla-firefox/firefox js-reviewInstalls for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).
$ npx skills add mozilla-firefox/firefox --skill js-review -a github-copilotProject install goes to .agents/skills/; add -g for ~/.copilot/skills/.
$ git clone --depth 1 https://github.com/mozilla-firefox/firefox.git skills-src && mkdir -p .github/skills && cp -r skills-src/.agents/skills/js-review .github/skills/js-review && rm -rf skills-srcUse ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.
GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/
Install the "js-review" agent skill from https://github.com/mozilla-firefox/firefox/tree/main/.agents/skills/js-review into .github/skills/js-review/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "js-review", then confirm the skill loads.GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add mozilla-firefox/firefox --skill js-review -a opencodeOpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.
$ gh skill install mozilla-firefox/firefox js-review --agent opencodeProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/mozilla-firefox/firefox.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/.agents/skills/js-review .opencode/skills/js-review && rm -rf skills-srcUse ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.
OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/
Install the "js-review" agent skill from https://github.com/mozilla-firefox/firefox/tree/main/.agents/skills/js-review into .opencode/skills/js-review/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "js-review", then confirm the skill loads.OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
Facts
- Skill name
js-review- GitHub stars
- 13k
- Token cost
- ~704 tokens
- SKILL.md length
- 408 words
- Files
- 1
- Skills in repo
- 7
- Repo updated
- First seen
- Licence
- Custom licence
At a glance
A skill your agent uses when reviewing code the JS engine (SpiderMonkey, js/src/) or self-reviewing code while producing it.
- Reviewing code the JS engine (SpiderMonkey
- SKILL.md covers Garbage Collected Data, Cross-Compartment Wrappers, Side Effects and JIT Concerns, plus 2 more sections
- Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
- Self-reviewing code while producing it
What it does
JS Review is an agent skill from mozilla-firefox/firefox. Use this skill when reviewing code the JS engine (SpiderMonkey, js/src/) or self-reviewing code while producing it.
Its SKILL.md is about 700 tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.
It sits in Development. The repository describes itself as: The official repository of Mozilla's Firefox web browser.
When your agent uses it
- Reviewing code the JS engine (SpiderMonkey
- Self-reviewing code while producing it
Example prompts
- “/js-review”
What it can do on your machine
Read from SKILL.md and the folder at commit 59c8a94. It shows what the files ask for, not the result of running them.
Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
No scripts in the folder and no shell commands in SKILL.md.
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.
Context cost
JS Review loads about 704 tokens when it runs. Until then it costs about 31 tokens; SKILL.md has 408 words of instructions outside code blocks.
Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.
Safety
Auto-check passed
The automated check found no risky patterns in SKILL.md.
Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.
SKILL.md
Its licence (Custom licence) doesn't allow us to republish the file, so here is its outline and opening line. It has 408 words (~704 tokens).
- name
- js-review
Files
Just SKILL.md in .agents/skills/js-review of mozilla-firefox/firefox.
Open the folder on GitHubat commit 59c8a94
Compare with similar skills
JS Review next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.
| Skill | Stars | Used in | Tokens | Auto-check | Licence | Repo updated |
|---|---|---|---|---|---|---|
| JS Review this skillmozilla-firefox/firefox | 13k | — | ~704 | Automated safety check: Pass | Custom licence | |
| Vercel Composition Patternssupabase/supabase | 111k | 59 repos | ~726 | Automated safety check: Pass | MIT | |
| Finishing a Development Branchobra/superpowers | 296k | 5 repos | ~1.9k | Automated safety check: Pass | MIT | |
| Typescript Advanced Typesrolling-scopes/rsschool-app | 10k | 25 repos | ~4.2k | Automated safety check: Pass | MPL-2.0 | |
| PR Babysitteropeninterpreter/openinterpreter | 69k | 3 repos | ~4.2k | Automated safety check: Pass | Apache-2.0 | |
| Code Review ChecklistshareAI-lab/learn-claude-code | 78k | 5 repos | ~1.1k | Automated safety check: Pass | MIT |
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- Official
Finishing a Development Branch
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Walks the last step of a branch: confirm tests pass, detect the git environment, ask how to integrate, carry out your choice and clean up the worktree.
Typescript Advanced Types
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Master TypeScript's advanced type system including generics, conditional types, mapped types, template literals, and utility types for building type-safe applications.
PR Babysitter
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Watches an open GitHub pull request until it merges, handling review comments, diagnosing CI failures and retrying flaky checks along the way.
Code Review Checklist
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Reviews code against a five-part checklist covering security, correctness, performance, maintainability and testing, and reports findings in a fixed format.
Greploop
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Iteratively improves a PR (GitHub), MR (GitLab), or shelved changelist (Perforce) until Greptile gives it a 5/5 confidence score with zero unresolved comments.
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Stack Reorganize
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Reorganize a range of local commits so each one stands on its own for review, by splitting, reordering, squashing or dropping them.
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Split one large or hard-to-review commit into several commits that each stand on their own for review, in a git or a Jujutsu (jj) checkout.
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Guidelines to follow when committing, or amending commits. An agent skill from mozilla-firefox/firefox.
Related
Categories
Questions about JS Review
What does JS Review do?
A skill your agent uses when reviewing code the JS engine (SpiderMonkey, js/src/) or self-reviewing code while producing it. JS Review is an agent skill from mozilla-firefox/firefox. Use this skill when reviewing code the JS engine (SpiderMonkey, js/src/) or self-reviewing code while producing it.
When should I use JS Review?
JS Review fits situations like: reviewing code the JS engine (SpiderMonkey; self-reviewing code while producing it.
How do I install JS Review in Claude Code?
Run `npx skills add mozilla-firefox/firefox --skill js-review -a claude-code`. Or copy the skill folder (.agents/skills/js-review in mozilla-firefox/firefox) into .claude/skills/js-review in your project. Claude Code loads it when a task matches its description.
How do I install JS Review in Codex?
Run `npx skills add mozilla-firefox/firefox --skill js-review -a codex`. Or copy the skill folder (.agents/skills/js-review in mozilla-firefox/firefox) into .agents/skills/js-review in your project. Codex loads it when a task matches its description.
Can I use JS Review in Cursor, Gemini CLI or GitHub Copilot?
Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add mozilla-firefox/firefox --skill js-review -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/js-review, .gemini/skills/js-review, .github/skills/js-review and .opencode/skills/js-review in your project.
What does JS Review need to run?
SKILL.md names no scripts, command-line tools or credentials: JS Review is instructions for the agent only.
Does JS Review access the network?
SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.
Is JS Review safe to install?
Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.
What licence does JS Review use?
JS Review has a licence file (the repository's licence) that doesn't match a standard licence. Read it on GitHub before reusing the skill.
How many tokens does JS Review use?
About 704 tokens (SKILL.md is roughly 2.8k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.
What are the alternatives to JS Review?
Skills that share tags, products or a category with JS Review: Vercel Composition Patterns (supabase/supabase, 111k stars), Finishing a Development Branch (obra/superpowers, 296k stars), Typescript Advanced Types (rolling-scopes/rsschool-app, 10k stars) and PR Babysitter (openinterpreter/openinterpreter, 69k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.
Who maintains JS Review?
mozilla-firefox (a GitHub organization) maintains it in mozilla-firefox/firefox, which has 13,384 GitHub stars. The repository holds 7 skills in this directory. The repository was last updated on October 8, 2026.
Source: mozilla-firefox/firefox on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.