Hi

\"\n});\n```\n\n## Val Town Utility Functions\n\nVal Town provides several utility functions to help with common project tasks.\n\n### Importing Utilities\nAlways import utilities with version pins to avoid breaking changes:\n```ts\nimport { parseProject, readFile, serveFile } from \"https://esm.town/v/std/utils@85-main/index.ts\";\n```\n\n### Available Utilities\n\n1. **parseProject** - Extract information about the current project from import.meta.url:\n```ts\nconst projectVal = parseProject(import.meta.url);\nconsole.log(projectVal.username); // Owner of the project\nconsole.log(projectVal.name); // Project name\nconsole.log(projectVal.version); // Version number\nconsole.log(projectVal.branch); // Branch name\nconsole.log(projectVal.links.self.project); // URL to the project page\n```\n\n2. **readFile** - Read files from within the project:\n```ts\n// Read a file from the project\nconst fileContent = await readFile(\"/frontend/index.html\", import.meta.url);\n```\n\n3. **serveFile** - Serve project files with proper content types:\n```ts\n// Serve a file from the project with proper Content-Type header\napp.get(\"/public/style.css\", c => serveFile(\"/frontend/style.css\", import.meta.url));\n```\n\n4. **listFiles** - List all files in the project:\n```ts\nconst files = await listFiles(import.meta.url);\n```\n\n5. **fetchTranspiledJavaScript** - Fetch and transpile TypeScript to JavaScript:\n```ts\nconst jsCode = await fetchTranspiledJavaScript(\"https://esm.town/v/username/project/path/to/file.ts\");\n```\n\n6. **testServer** - Create a test server for running test suites:\n```ts\nexport default testServer([\n {\n name: \"Feature Tests\",\n tests: [\n {\n name: \"should add numbers correctly\",\n function: () => {\n expect(1 + 1).toBe(2);\n },\n }\n ],\n }\n]);\n```\n\n## Val Town Platform Specifics\n- **Redirects:** Use `return new Response(null, { status: 302, headers: { Location: \"/place/to/redirect\" }})` instead of `Response.redirect` which is broken\n- **Images:** Avoid external images or base64 images. Use emojis, unicode symbols, or icon fonts/libraries instead\n- For AI-generated images, use: `https://maxm-imggenurl.web.val.run/the-description-of-your-image`\n- **Storage:** DO NOT use the Deno KV module for storage\n- **Browser APIs:** DO NOT use the `alert()`, `prompt()`, or `confirm()` methods\n- **Weather Data:** Use open-meteo for weather data (doesn't require API keys) unless otherwise specified\n- **View Source:** Add a view source link with `import.meta.url.replace(\"esm.town\", \"val.town\")` and include `target=\"_top\"` attribute\n- **Error Debugging:** Add `` to HTML to capture client-side errors\n- **Error Handling:** Only use try...catch when there's a clear local resolution; avoid catches that merely log or return 500s - let errors bubble up with full context\n- **Environment Variables:** Use `Deno.env.get('keyname')` and minimize their use - prefer APIs without keys\n- **Imports:** Use `https://esm.sh` for npm and Deno dependencies to ensure compatibility on server and browser\n- **Storage Strategy:** Only use backend storage if explicitly required; prefer simple static client-side sites\n- For persistence, use Val Town SQLite or Blob storage with `import.meta.url` for keys/table names\n- **React Configuration:** When using React libraries, pin versions with `?deps=react@18.2.0,react-dom@18.2.0` and include the `@jsxImportSource` pragma\n- When facing client-side render issues, check if all React dependencies are pinned to the same version\n- **Styling:** Default to using TailwindCSS via `` unless otherwise specified\n\n## Project Structure and Design Patterns\n\n### Recommended Directory Structure\n```\n├── backend/\n│ ├── database/\n│ │ ├── migrations.ts # Schema definitions\n│ │ ├── queries.ts # DB query functions\n│ │ └── README.md\n│ ├── index.ts # Main entry point\n│ └── README.md\n├── frontend/\n│ ├── components/\n│ │ ├── App.tsx\n│ │ └── [Component].tsx\n│ ├── favicon.svg\n│ ├── index.html # Main HTML template\n│ ├── index.tsx # JS entry point\n│ ├── README.md\n│ └── style.css\n├── README.md\n└── shared/\n ├── README.md\n └── utils.ts # Shared types and functions\n```\n\n### Backend (Hono) Best Practices\n- Hono is the recommended API framework (similar to Express, Flask, or Sinatra)\n- Main entry point should be `backend/index.ts`\n- **Static asset serving:** Use the utility functions to read and serve project files:\n ```ts\n // Use the serveFile utility to handle content types automatically\n app.get(\"/public/*\", c => serveFile(c.req.path.replace(\"/public\", \"/frontend\"), import.meta.url));\n\n // For index.html, often you'll want to bootstrap with initial data\n app.get(\"/\", async c => {\n let html = await readFile(\"/frontend/index.html\", import.meta.url);\n\n // Inject data to avoid extra round-trips\n const initialData = await fetchInitialData();\n const dataScript = ``;\n\n html = html.replace(\"\", `${dataScript}`);\n return c.html(html);\n });\n ```\n- Create RESTful API routes for CRUD operations\n- Be careful with error handling as Hono tends to swallow errors\n- Always include this snippet at the top-level Hono app to re-throwing errors to see full stack traces:\n ```ts\n // Unwrap Hono errors to see original error details\n app.onError((err, c) => {\n throw err;\n });\n ```\n\n### Frontend Best Practices\n- Structure as a standard client-side React app\n- Use SVG for favicons (Val Town only supports text files)\n- Separate components into individual files\n- Access bootstrapped data from `window.__INITIAL_DATA__`\n- Use React 18.2.0 consistently in all imports and the `@jsxImportSource` pragma\n- Follow the React component pattern from the example project\n- Handle API calls properly with proper error catching\n\n### Database Patterns\n- Run migrations on startup or comment out for performance\n- Change table names when modifying schemas rather than altering\n- Export clear query functions with proper TypeScript typing\n- Follow the queries and migrations pattern from the example\n\n## Common Gotchas and Solutions\n\n1. **Environment Limitations:**\n - Val Town runs on Deno in a serverless context, not Node.js\n - Code in `shared/` must work in both frontend and backend environments\n - Cannot use `Deno` keyword in shared code\n - Use `https://esm.sh` for imports that work in both environments\n\n2. **SQLite Peculiarities:**\n - Limited support for ALTER TABLE operations\n - Create new tables with updated schemas and copy data when needed\n - Always run table creation before querying\n\n3. **React Configuration:**\n - All React dependencies must be pinned to 18.2.0\n - Always include `@jsxImportSource https://esm.sh/react@18.2.0` at the top of React files\n - Rendering issues often come from mismatched React versions\n\n4. **File Handling:**\n - Val Town only supports text files, not binary\n - Use the provided utilities to read files across branches and forks\n - For files in the project, use `readFile` helpers\n\n5. **API Design:**\n - `fetch` handler is the entry point for HTTP vals\n - Run the Hono app with `export default app.fetch // This is the entry point for HTTP vals`\n - Properly handle CORS if needed for external access","deleted","label",[98],"permalink","https://www.val.town/x/zhichu/stevensDemo/code/.cursorrules","extension","cursorrules","actionData","errors"]