Crxjs

What it does

When your agent uses it

• The user mentions CRXJS
• @crxjs/vite-plugin
• Extension with hot reload
• HMR for chrome extension

Example prompts

• “extension with hot reload”
• “HMR for chrome extension”
• “Use the crxjs skill to crxj Chrome extension development — true HMR for popup, options, content scripts, side panels, manifest-driven builds…”
• “/crxjs”

Requirements

• Node.js
• Compatibility (from SKILL.md): Designed for Claude Code, Codex or similar harness. Requires git, node.
• Pre-approved tools (allowed-tools): Read, Edit, Write, Glob, Grep, Bash(git:*), Bash(gh:*), Bash(npm:*)

What it can do on your machine

Read from SKILL.md and the folder at commit 123cb15. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves these tools, so the agent can use them without asking each time:

  • Read
  • Edit
  • Write
  • Glob
  • Grep
  • Bash(git:*)
  • Bash(gh:*)
  • Bash(npm:*)

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  Shell commands in SKILL.md call:

  • npm

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  No URLs in SKILL.md. Its commands use npm, which can reach the network depending on how they are called.

  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.

• Compatibility

  Designed for Claude Code, Codex or similar harness. Requires git, node.

  From compatibility in the SKILL.md frontmatter.

Context cost

Crxjs loads about 2.6k tokens when it runs. Until then it costs about 192 tokens; SKILL.md has 646 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~192

When it runs · the whole SKILL.md, loaded when a task matches

~2.6k

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

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

The full file from samber/cc-skills at commit 123cb15, republished under its MIT licence (© samber). 646 words, ~2,582 tokens.

name

crxjs

description

CRXJS Chrome extension development — true HMR for popup, options, content scripts, side panels, manifest-driven builds, dynamic content script imports (`?script`, `?script&module`), and `defineManifest` for type-safe manifests. Uses Vite as its build tool. Use when the user mentions CRXJS, crxjs, @crxjs/vite-plugin, 'extension with hot reload', 'HMR for chrome extension', or wants to set up a CRXJS-based Chrome extension project with any framework (React, Vue, Svelte, Solid, Vanilla). Also trigger when the user has an existing CRXJS project and wants to add features, fix HMR issues, or configure content scripts with CRXJS. For general Chrome extension architecture (messaging, CSP, storage, permissions) -> See `samber/cc-skills@chrome-extension` skill.

allowed-tools

Read, Edit, Write, Glob, Grep, Bash(git:*), Bash(gh:*), Bash(npm:*)

compatibility

Designed for Claude Code, Codex or similar harness. Requires git, node.

user-invocable

true

license

MIT

metadata.author

samber

metadata.version

1.1.0

# Scaffold new project (picks framework interactively)
npm create crxjs@latest

# Or add to existing Vite project
npm install @crxjs/vite-plugin -D

// vite.config.ts
import { defineConfig } from "vite";
import react from "@vitejs/plugin-react";
import { crx } from "@crxjs/vite-plugin";
import manifest from "./manifest.json";

export default defineConfig({
  plugins: [react(), crx({ manifest })],
});

import { ManifestV3Export } from "@crxjs/vite-plugin";
const manifest = manifestJson as ManifestV3Export;

import vue from "@vitejs/plugin-vue";
import { crx } from "@crxjs/vite-plugin";
import manifest from "./manifest.json";

export default defineConfig({
  plugins: [vue(), crx({ manifest })],
});

import { svelte } from "@sveltejs/vite-plugin-svelte";
import { crx } from "@crxjs/vite-plugin";
import manifest from "./manifest.json";

export default defineConfig({
  plugins: [svelte(), crx({ manifest })],
});

import { crx } from "@crxjs/vite-plugin";
import manifest from "./manifest.json";

export default defineConfig({
  plugins: [crx({ manifest })],
});

// manifest.ts
import { defineManifest } from "@crxjs/vite-plugin";
import pkg from "./package.json";

export default defineManifest((config) => ({
  manifest_version: 3,
  name: config.command === "serve" ? `[DEV] ${pkg.name}` : pkg.name,
  version: pkg.version,
  description: pkg.description,
  permissions: ["storage", "activeTab", "scripting"],
  action: {
    default_popup: "src/popup/index.html",
    default_icon: {
      "16": "public/icons/icon16.png",
      "48": "public/icons/icon48.png",
    },
  },
  background: {
    service_worker: "src/background/index.ts",
    type: "module",
  },
  content_scripts: [
    {
      matches: ["https://*/*"],
      js: ["src/content/index.ts"],
      css: ["src/content/styles.css"],
    },
  ],
  options_page: "src/options/index.html",
  side_panel: { default_path: "src/sidepanel/index.html" },
  icons: {
    "16": "public/icons/icon16.png",
    "48": "public/icons/icon48.png",
    "128": "public/icons/icon128.png",
  },
}));

import manifest from "./manifest";
// ... crx({ manifest })

/// <reference types="@crxjs/vite-plugin/client" />

// background.ts — ?script gives you a resolved path for executeScript
import contentScript from "./content?script";

chrome.action.onClicked.addListener(async (tab) => {
  await chrome.scripting.executeScript({
    target: { tabId: tab.id! },
    files: [contentScript],
  });
});

import mainWorldScript from "./inject?script&module";

await chrome.scripting.executeScript({
  target: { tabId },
  world: "MAIN",
  files: [mainWorldScript],
});

crx({
  manifest,
  browser: "chrome", // 'chrome' | 'firefox'
  contentScripts: {
    injectCss: true, // auto-inject CSS for content scripts
    hmrTimeout: 5000, // HMR connection timeout (ms)
  },
});

# Start dev server (outputs to dist/ with HMR)
npm run dev

# 1. Open chrome://extensions
# 2. Enable "Developer mode"
# 3. Click "Load unpacked"
# 4. Select the dist/ directory
# 5. Edit code — popup/content scripts update instantly via HMR
# 6. Service worker changes trigger automatic extension reload

npm run build    # outputs to dist/

cd dist && zip -r ../extension.zip .

build: {
  modulePreload: false;
}

server: {
  port: 5173,
  strictPort: true,
  hmr: { port: 5173 },
}

my-extension/
├── src/
│   ├── background/
│   │   └── index.ts
│   ├── content/
│   │   ├── index.ts
│   │   └── styles.css
│   ├── popup/
│   │   ├── index.html        <- CRXJS resolves HTML entry points
│   │   ├── App.tsx
│   │   └── main.tsx
│   ├── options/
│   │   ├── index.html
│   │   └── main.tsx
│   ├── sidepanel/
│   │   ├── index.html
│   │   └── main.tsx
│   └── shared/
│       ├── messages.ts
│       └── storage.ts
├── public/
│   └── icons/
├── manifest.ts               <- or manifest.json
├── vite.config.ts
├── tsconfig.json
└── package.json

© samber, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in skills/crxjs of samber/cc-skills.

Open the folder on GitHubat commit 123cb15