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cloudflare-worker-base

Included with Lifetime
$97 forever

Set up Cloudflare Workers with Hono routing, Vite plugin, and Static Assets using production-tested patterns. Prevents 6 errors: export syntax, routing conflicts, HMR crashes, and Service Worker format confusion. Use when: creating Workers projects, configuring Hono or Vite for Workers, deploying with Wrangler, adding Static Assets with SPA fallback, or troubleshooting export syntax, API route conflicts, scheduled handlers, or HMR race conditions. Keywords: Cloudflare Workers, CF Workers, Hono, wrangler, Vite, Static Assets, @cloudflare/vite-plugin, wrangler.jsonc, ES Module, run_worker_first, SPA fallback, API routes, serverless, edge computing, "Cannot read properties of undefined", "Static Assets 404", "A hanging Promise was canceled", "Handler does not export", deployment fails, routing not working, HMR crashes

Backend & APIs

What this skill does


# Cloudflare Worker Base Stack

**Production-tested**: cloudflare-worker-base-test (https://cloudflare-worker-base-test.webfonts.workers.dev)
**Last Updated**: 2025-10-20
**Status**: Production Ready ✅

---

## Quick Start (5 Minutes)

### 1. Scaffold Project

```bash
npm create cloudflare@latest my-worker -- \
  --type hello-world \
  --ts \
  --git \
  --deploy false \
  --framework none
```

**Why these flags:**
- `--type hello-world`: Clean starting point
- `--ts`: TypeScript support
- `--git`: Initialize git repo
- `--deploy false`: Don't deploy yet (configure first)
- `--framework none`: We'll add Vite ourselves

### 2. Install Dependencies

```bash
cd my-worker
npm install [email protected]
npm install -D @cloudflare/[email protected] vite@^7.0.0
```

**Version Notes:**
- `[email protected]`: Latest stable (verified 2025-10-20)
- `@cloudflare/[email protected]`: Latest stable, fixes HMR race condition
- `vite`: Latest version compatible with Cloudflare plugin

### 3. Configure Wrangler

Create or update `wrangler.jsonc`:

```jsonc
{
  "$schema": "node_modules/wrangler/config-schema.json",
  "name": "my-worker",
  "main": "src/index.ts",
  "account_id": "YOUR_ACCOUNT_ID", // Find this in your Cloudflare dashboard (Workers & Pages -> Overview).
  "compatibility_date": "2025-10-11",
  "observability": {
    "enabled": true
  },
  "assets": {
    "directory": "./public/",
    "binding": "ASSETS",
    "not_found_handling": "single-page-application",
    "run_worker_first": ["/api/*"]
  }
}
```

**CRITICAL: `run_worker_first` Configuration**
- Without this, SPA fallback intercepts API routes
- API routes return `index.html` instead of JSON
- Source: [workers-sdk #8879](https://github.com/cloudflare/workers-sdk/issues/8879)

### 4. Configure Vite

Create `vite.config.ts`:

```typescript
import { defineConfig } from 'vite'
import { cloudflare } from '@cloudflare/vite-plugin'

export default defineConfig({
  plugins: [
    cloudflare({
      // Optional: Configure the plugin if needed
    }),
  ],
})
```

**Why @cloudflare/vite-plugin:**
- Official plugin from Cloudflare
- Supports HMR with Workers
- Enables local development with Miniflare
- Version 1.13.13 fixes "A hanging Promise was canceled" error

---

## The Four-Step Setup Process

### Step 1: Create Hono App with API Routes

Create `src/index.ts`:

```typescript
/**
 * Cloudflare Worker with Hono
 *
 * CRITICAL: Export pattern to prevent build errors
 * ✅ CORRECT: export default app
 * ❌ WRONG:   export default { fetch: app.fetch }
 */

import { Hono } from 'hono'

// Type-safe environment bindings
type Bindings = {
  ASSETS: Fetcher
}

const app = new Hono<{ Bindings: Bindings }>()

/**
 * API Routes
 * Handled BEFORE static assets due to run_worker_first config
 */
app.get('/api/hello', (c) => {
  return c.json({
    message: 'Hello from Cloudflare Workers!',
    timestamp: new Date().toISOString(),
  })
})

app.get('/api/health', (c) => {
  return c.json({
    status: 'ok',
    version: '1.0.0',
    environment: c.env ? 'production' : 'development',
  })
})

/**
 * Fallback to Static Assets
 * Any route not matched above is served from public/ directory
 */
app.all('*', (c) => {
  return c.env.ASSETS.fetch(c.req.raw)
})

/**
 * Export the Hono app directly (ES Module format)
 * This is the correct pattern for Cloudflare Workers with Hono + Vite
 */
export default app
```

**Why This Export Pattern:**
- Source: [honojs/hono #3955](https://github.com/honojs/hono/issues/3955)
- Using `{ fetch: app.fetch }` causes: "Cannot read properties of undefined (reading 'map')"
- Exception: If you need scheduled/tail handlers, use Module Worker format:
  ```typescript
  export default {
    fetch: app.fetch,
    scheduled: async (event, env, ctx) => { /* ... */ }
  }
  ```

### Step 2: Create Static Frontend

Create `public/index.html`:

```html
<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>My Worker App</title>
  <link rel="stylesheet" href="/styles.css">
</head>
<body>
  <div class="container">
    <h1>Cloudflare Worker + Static Assets</h1>
    <button onclick="testAPI()">Test API</button>
    <pre id="output"></pre>
  </div>
  <script src="/script.js"></script>
</body>
</html>
```

Create `public/script.js`:

```javascript
async function testAPI() {
  const response = await fetch('/api/hello')
  const data = await response.json()
  document.getElementById('output').textContent = JSON.stringify(data, null, 2)
}
```

Create `public/styles.css`:

```css
body {
  font-family: system-ui, -apple-system, sans-serif;
  max-width: 800px;
  margin: 40px auto;
  padding: 20px;
}

button {
  background: #0070f3;
  color: white;
  border: none;
  padding: 12px 24px;
  border-radius: 6px;
  cursor: pointer;
}

pre {
  background: #f5f5f5;
  padding: 16px;
  border-radius: 6px;
  overflow-x: auto;
}
```

### Step 3: Update Package Scripts

Update `package.json`:

```json
{
  "scripts": {
    "dev": "wrangler dev",
    "deploy": "wrangler deploy",
    "cf-typegen": "wrangler types"
  }
}
```

### Step 4: Test & Deploy

```bash
# Generate TypeScript types for bindings
npm run cf-typegen

# Start local dev server (http://localhost:8787)
npm run dev

# Deploy to production
npm run deploy
```

---

## Known Issues Prevention

This skill prevents **6 documented issues**:

### Issue #1: Export Syntax Error
**Error**: "Cannot read properties of undefined (reading 'map')"
**Source**: [honojs/hono #3955](https://github.com/honojs/hono/issues/3955)
**Prevention**: Use `export default app` (NOT `{ fetch: app.fetch }`)

### Issue #2: Static Assets Routing Conflicts
**Error**: API routes return `index.html` instead of JSON
**Source**: [workers-sdk #8879](https://github.com/cloudflare/workers-sdk/issues/8879)
**Prevention**: Add `"run_worker_first": ["/api/*"]` to wrangler.jsonc

### Issue #3: Scheduled/Cron Not Exported
**Error**: "Handler does not export a scheduled() function"
**Source**: [honojs/vite-plugins #275](https://github.com/honojs/vite-plugins/issues/275)
**Prevention**: Use Module Worker format when needed:
```typescript
export default {
  fetch: app.fetch,
  scheduled: async (event, env, ctx) => { /* ... */ }
}
```

### Issue #4: HMR Race Condition
**Error**: "A hanging Promise was canceled" during development
**Source**: [workers-sdk #9518](https://github.com/cloudflare/workers-sdk/issues/9518)
**Prevention**: Use `@cloudflare/[email protected]` or later

### Issue #5: Static Assets Upload Race
**Error**: Non-deterministic deployment failures in CI/CD
**Source**: [workers-sdk #7555](https://github.com/cloudflare/workers-sdk/issues/7555)
**Prevention**: Use Wrangler 4.x+ with retry logic (fixed in recent versions)

### Issue #6: Service Worker Format Confusion
**Error**: Using deprecated Service Worker format
**Source**: Cloudflare migration guide
**Prevention**: Always use ES Module format (shown in Step 1)

---

## Configuration Files Reference

### wrangler.jsonc (Full Example)

```jsonc
{
  "$schema": "node_modules/wrangler/config-schema.json",
  "name": "my-worker",
  "main": "src/index.ts",
  "account_id": "YOUR_ACCOUNT_ID", // Find this in your Cloudflare dashboard (Workers & Pages -> Overview).
  "compatibility_date": "2025-10-11",
  "observability": {
    "enabled": true
  },
  "assets": {
    "directory": "./public/",
    "binding": "ASSETS",
    "not_found_handling": "single-page-application",
    "run_worker_first": ["/api/*"]
  }
  /* Optional: Environment Variables */
  // "vars": { "MY_VARIABLE": "production_value" }

  /* Optional: KV Namespace Bindings */
  // "kv_namespaces": [
  //   { "binding": "MY_KV", "id": "YOUR_KV_ID" }
  // ]

  /* Optional: D1 Database Bindings */
  // "d1_databases": [
  //   { "binding": "DB", "database_name": "my-db", "database_id": "YOUR_DB_ID" }
  // ]

  /* Optional: R2 Bucket Bindings */
  // "r2_buckets": [
  //   { "binding": "MY_BUCKET", "bucket_name": "my-bucket" }

Related in Backend & APIs