# Page Not Found

The URL `files/U5EsnoTkK77BU6KRmDIU` does not exist. This page may have been moved, renamed, or deleted.

## Suggested Pages

You may be looking for one of the following:
- [Angular](https://petercheng7788.gitbook.io/developer-note/frontend/angular.md)
- [React Router Dom](https://petercheng7788.gitbook.io/developer-note/frontend/react/routing/react-router-dom.md)
- [Progressive Web App (PWA)](https://petercheng7788.gitbook.io/developer-note/frontend/progressive-web-app-pwa.md)
- [Search Engine Optimiaztion (SEO)](https://petercheng7788.gitbook.io/developer-note/frontend/search-engine-optimiaztion-seo.md)
- [Web Security](https://petercheng7788.gitbook.io/developer-note/frontend/web-security.md)

## How to find the correct page

If the exact page cannot be found, you can still retrieve the information using the documentation query interface.

### Option 1 — Ask a question (recommended)

Perform an HTTP GET request on the documentation index with the `ask` parameter:

```
GET https://petercheng7788.gitbook.io/developer-note/frontend/angular.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

### Option 2 — Browse the documentation index

Full index: https://petercheng7788.gitbook.io/developer-note/sitemap.md

Use this to discover valid page paths or navigate the documentation structure.

### Option 3 — Retrieve the full documentation corpus

Full export: https://petercheng7788.gitbook.io/developer-note/llms-full.txt

Use this to access all content at once and perform your own parsing or retrieval. It will be more expensive.

## Tips for requesting documentation

Prefer `.md` URLs for structured content, append `.md` to URLs (e.g., `/developer-note/frontend/angular.md`).

You may also use `Accept: text/markdown` header for content negotiation.