react-expert

react-expert is a skill for Claude Code, Codex from eric861129/SKILLS_All-in-one. It costs 79 tokens per session (1,199 once invoked), scanned A, a copy of react-expert, MIT.

A coding guide for React, a JavaScript library for building interactive web interfaces, including newer React and Next.js projects. It covers components, data, state, forms, testing, and fixing type errors.

In plain words
What is it for?
Use it to build React components, custom hooks, forms, data-fetching flows, and state management. It also supports testing, performance improvements, and moving older class components to functions.
Why use it?
It gives the agent a consistent process for planning React code, checking it, and correcting problems before delivery. It helps avoid rendering, accessibility, and TypeScript errors.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to build React components, custom hooks, forms, data-fetching flows, and state management. It also supports testing, performance improvements, and moving older class components to functions.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/eric861129/skills_all-in-one/react-expert
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 eric861129/SKILLS_All-in-one --skill react-expert
Clone the repo
git clone --depth 1 https://github.com/eric861129/SKILLS_All-in-one

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 react-expert

README.md
[![agentmods](https://agentmods.dev/badge/skills/eric861129/skills_all-in-one/react-expert/github.svg)](https://agentmods.dev/skills/eric861129/skills_all-in-one/react-expert)
Your own site
<a href="https://agentmods.dev/skills/eric861129/skills_all-in-one/react-expert"><img src="https://agentmods.dev/badge/skills/eric861129/skills_all-in-one/react-expert/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 react-expert

Your own site · 80×15
<a href="https://agentmods.dev/skills/eric861129/skills_all-in-one/react-expert"><img src="https://agentmods.dev/badge/skills/eric861129/skills_all-in-one/react-expert.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 79 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,199 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.
Origin 95% copy Near-identical to another mod 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 $0.00079 $0.01199
Opus 5 $0.00039 $0.00600
Sonnet 5 $0.00016 $0.00240
Haiku 4.5 $0.00008 $0.00120

Measured 9d ago against content hash f349e26b8743, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

react-expert 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 9d ago.

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.

Origin

This is a copy

95% identical to react-expert — 2 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.agent/skills/react-expert/SKILL.md · 150 lines

How it starts

The opening of the file, as written. The whole thing — 150 lines — stays where its author put it; the contents beside it link to each section on GitHub.

React Expert

Senior React specialist with deep expertise in React 19, Server Components, and production-grade application architecture.

When to Use This Skill

  • Building new React components or features
  • Implementing state management (local, Context, Redux, Zustand)
  • Optimizing React performance
  • Setting up React project architecture
  • Working with React 19 Server Components
  • Implementing forms with React 19 actions
  • Data fetching patterns with TanStack Query or use()

Core Workflow

  1. Analyze requirements - Identify component hierarchy, state needs, data flow
  2. Choose patterns - Select appropriate state management, data fetching approach
  3. Implement - Write TypeScript components with proper types
  4. Validate - Run tsc --noEmit; if it fails, review reported errors, fix all type issues, and re-run until clean before proceeding
  5. Optimize - Apply memoization where needed, ensure accessibility; if new type errors are introduced, return to step 4
  6. Test - Write tests with React Testing Library; if any assertions fail, debug and fix before submitting

Reference Guide

Load detailed guidance based on context:

Topic Reference Load When
Server Components references/server-components.md RSC patterns, Next.js App Router
React 19 references/react-19-features.md use() hook, useActionState, forms
State Management references/state-management.md Context, Zustand, Redux, TanStack
Hooks references/hooks-patterns.md Custom hooks, useEffect, useCallback
Performance references/performance.md memo, lazy, virtualization
Testing references/testing-react.md Testing Library, mocking
Class Migration references/migration-class-to-modern.md Converting class components to hooks/RSC

Key Patterns

Server Component (Next.js App Router)

// app/users/page.tsx — Server Component, no "use client"
import { db } from '@/lib/db';

interface User {
  id: string;
  name: string;
}

export default async function UsersPage() {
  const users: User[] = await db.user.findMany();

  return (
    <ul>
      {users.map((user) => (
        <li key={user.id}>{user.name}</li>
      ))}
    </ul>
  );
}

Read the full file on GitHub · 150 lines

Files

What ships with it

7 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 9d ago First seen · 150 lines · 79 tokens per session scan A f349e26b8743

Subscribe to this mod's changes

react-expert is a skill published in the GitHub repository eric861129/SKILLS_All-in-one (52 stars, last pushed 4mo ago), licensed MIT. It adds 79 tokens to every session and 1,199 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. It is 95% identical to react-expert, differing in 2 lines, and is treated as a copy.