> For the complete documentation index, see [llms.txt](https://docs.apryse.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.apryse.com/web/advanced/customizing-setup.md).

# Setup options when customizing WebViewer

Enhance WebViewer with customizations using two setup options: accessing the WebViewer instance within your app or utilizing a config file for standalone JavaScript execution inside WebViewer's iframe

There are two ways of adding customization to WebViewer, the first way is by accessing the WebViewer instance within your app and the second is by using a [config file](/web/advanced/config-files.md), which is a stand-alone JavaScript file executed inside [WebViewer's iframe](/web/what-is-webviewer/wv-inside.md#webviewers-iframe).

### Config file

You can organize your custom code in a separate JavaScript file that is executed in the context of the [iframe](/web/what-is-webviewer/wv-inside.md#webviewers-iframe). In this way, you have direct access to the iframe window and document, and you can use WebViewer's global methods directly. See more details about [config files](/web/advanced/config-files.md).

Config files are recommended when you are hosting the WebViewer lib folder on a separate server from your application. Since the config file is executed directly in the iframe there are no cross origin issues.

<pre class="language-js" data-line-numbers><code class="lang-js">// app.js
// Instantiate WebViewer
WebViewer({
  path: 'https://myotherserver.com/webviewer/lib',
  licenseKey: '<code class="expression">visitor.claims.wvKey || "YOUR_LICENSE_KEY"</code>'
  initialDoc: '/files/webviewer-demo-annotated.pdf',
  config: 'config.js' // path/to/your/config.js
}, document.getElementById('viewer'));
</code></pre>

{% tabs %}
{% tab title="JavaScript (SDK v8.0+)" %}
{% code lineNumbers="true" %}

```js
// config.js executed inside the iframe
instance.UI.addEventListener(instance.UI.Events.VIEWER_LOADED, () => {
  const { documentViewer, annotationManager } = instance.Core;

  // Add customization here
  documentViewer.setMargin(20);
  documentViewer.addEventListener('fitModeUpdated', fitMode => {
    console.log('fit mode changed');
  });

  instance.UI.disableElement('searchButton');
  instance.UI.setTheme('dark');
});

instance.UI.addEventListener(instance.UI.Events.DOCUMENT_LOADED, () => {
  const { documentViewer, annotationManager } = instance.Core;

  // Add customization here
  // Draw rectangle annotation on first page
  // "Annotations" can be directly accessed since we're inside the iframe
  const rectangle = new Annotations.RectangleAnnotation();
  rectangle.PageNumber = 1;
  rectangle.X = 100;
  rectangle.Y = 100;
  rectangle.Width = 250;
  rectangle.Height = 250;
  rectangle.Author = annotationManager.getCurrentUser();
  annotationManager.addAnnotation(rectangle);
  annotationManager.drawAnnotations(rectangle.PageNumber);
})
```

{% endcode %}
{% endtab %}

{% tab title="JavaScript (SDK v6.0+)" %}
{% code lineNumbers="true" %}

```js
// config.js executed inside the iframe
window.addEventListener('viewerLoaded', () => {
  const docViewer = readerControl.docViewer;
  const annotManager = docViewer.getAnnotationManager();

  // Add customization here
  docViewer.setMargin(20);
  docViewer.on('fitModeUpdated', fitMode => {
    console.log('fit mode changed');
  });

  readerControl.disableElement('searchButton');
  readerControl.setTheme('dark');
});

window.addEventListener('documentLoaded', () => {
  const docViewer = readerControl.docViewer;
  const annotManager = docViewer.getAnnotationManager();

  // Add customization here
  // Draw rectangle annotation on first page
  // "Annotations" can be directly accessed since we're inside the iframe
  const rectangle = new Annotations.RectangleAnnotation();
  rectangle.PageNumber = 1;
  rectangle.X = 100;
  rectangle.Y = 100;
  rectangle.Width = 250;
  rectangle.Height = 250;
  rectangle.Author = annotManager.getCurrentUser();
  annotManager.addAnnotation(rectangle);
  annotManager.drawAnnotations(rectangle.PageNumber);
})
```

{% endcode %}
{% endtab %}
{% endtabs %}


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://docs.apryse.com/web/advanced/customizing-setup.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.