## JavaScript-only settings { #javascript-only-settings }

Swagger UI also allows other configurations to be **JavaScript-only** objects (for example, JavaScript functions).

FastAPI also includes these JavaScript-only `presets` settings:

```JavaScript
presets: [
    SwaggerUIBundle.presets.apis,
    SwaggerUIBundle.SwaggerUIStandalonePreset
]

## Self-hosting JavaScript and CSS for docs { #self-hosting-javascript-and-css-for-docs }

Self-hosting the JavaScript and CSS could be useful if, for example, you need your app to keep working even while offline, without open Internet access, or in a local network.

    * une validation même pour les objets <abbr title="JavaScript Object Notation">JSON</abbr> profondément imbriqués.
* <abbr title="aussi connu sous le nom de : serialization, parsing, marshalling">Une conversion</abbr> des données d'entrée : venant du réseau et allant vers les données et types de Python, permettant de lire :
    * le <abbr title="JavaScript Object Notation">JSON</abbr>.

<a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS" class="external-link" target="_blank">CORS or "Cross-Origin Resource Sharing"</a> refers to the situations when a frontend running in a browser has JavaScript code that communicates with a backend, and the backend is in a different "origin" than the frontend.

## Origin { #origin }

If you go to the **API docs UI** at `/docs` you will be able to see the **documentation** for cookies for your *path operations*.

But even if you **fill the data** and click "Execute", because the docs UI works with **JavaScript**, the cookies won't be sent, and you will see an **error** message as if you didn't write any values.

    strategy:
      fail-fast: false
      matrix:
        # Override automatic language detection by changing the below list
        # Supported options are ['csharp', 'cpp', 'go', 'java', 'javascript', 'python']
        language: ['java', 'javascript']
        # Learn more...
        # https://docs.github.com/en/github/finding-security-vulnerabilities-and-errors-in-your-code/configuring-code-scanning#overriding-automatic-language-detection

import org.codelibs.fess.suggest.exception.SuggesterException;
import org.codelibs.fess.suggest.request.Response;

/**
 * <p>
 *   Deferred is a class that represents a deferred computation.
 *   It is similar to a Promise in JavaScript.
 *   It allows you to register callbacks that will be executed when the computation is complete,
 *   either successfully (resolve) or with an error (reject).
 * </p>
 *
 * <p>

Or you might have any other way to communicate with the WebSocket endpoint.

---

But for this example, we'll use a very simple HTML document with some JavaScript, all inside a long string.

This, of course, is not optimal and you wouldn't use it for production.

In production you would have one of the options above.

{* ../../docs_src/generate_clients/tutorial004.py *}

//// tab | Node.js

```Javascript
{!> ../../docs_src/generate_clients/tutorial004.js!}
```

////

### <a href="https://nestjs.com/" class="external-link" target="_blank">NestJS</a> (and <a href="https://angular.io/" class="external-link" target="_blank">Angular</a>) { #nestjs-and-angular }

This isn't even Python, NestJS is a JavaScript (TypeScript) NodeJS framework inspired by Angular.

It achieves something somewhat similar to what can be done with Flask-apispec.