> 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/get-started/samples/form-fields.md).

# Customize Form Fields - Sample Code

Use JavaScript to change the color and opacity of PDF form fields. Highlight required fields or draw attention to important fields in your PDF forms.

Change the color and opacity of PDF Form Fields using this JavaScript sample (no servers or other external dependencies required). This is commonly used to highlight required fields in a form (signature fields) or to make important fields easier to find on a page. This sample works on all browsers (including IE11) and mobile devices without using plug-ins. To see an example launch our [Form Field Customization demo](https://sdk.apryse.com/samples/web/samples/forms/form-fields/). Learn more about our [Web SDK](/web/get-started/guides.md).

{% tabs %}
{% tab title="JavaScript" %}
{% code lineNumbers="true" %}

```js
// eslint-disable-next-line no-undef
const WebViewerConstructor = isWebComponent() ? WebViewer.WebComponent : WebViewer;

WebViewerConstructor(
  {
    path: '../../../lib',
    initialDoc: 'https://pdftron.s3.amazonaws.com/downloads/pl/form1.pdf',
  },
  document.getElementById('viewer')
).then(instance => {
  samplesSetup(instance);
  const { documentViewer, annotationManager, Annotations } = instance.Core;

  documentViewer.addEventListener('documentLoaded', () => {
    const pageCount = documentViewer.getPageCount();
    const defaultStyles = Annotations.WidgetAnnotation.getCustomStyles;
    const defaultContainerStyles = Annotations.WidgetAnnotation.getContainerCustomStyles;
    const customStyles = widget => {
      if (widget instanceof Annotations.TextWidgetAnnotation) {
        if (widget.fieldName === 'f1-1') {
          return {
            'background-color': 'lightgreen',
          };
        }
        return {
          'background-color': 'lightblue',
          color: 'brown',
        };
      }
      if (widget instanceof Annotations.PushButtonWidgetAnnotation) {
        return {
          'background-color': 'red',
          color: 'white',
        };
      }
    };

    const customContainerStyles = widget => {
      if (widget instanceof Annotations.WidgetAnnotation) {
        return {
          border: '2px solid green',
        };
      }
    };

    document.getElementById('form').onchange = e => {
      if (e.target.id === 'custom') {
        // Change styles for widget annotations
        Annotations.WidgetAnnotation.getCustomStyles = customStyles;
        Annotations.WidgetAnnotation.getContainerCustomStyles = customContainerStyles;
      } else {
        Annotations.WidgetAnnotation.getCustomStyles = defaultStyles;
        Annotations.WidgetAnnotation.getContainerCustomStyles = defaultContainerStyles;
      }
      for (let i = 0; i < pageCount; i++) {
        // Redraw canvas
        annotationManager.drawAnnotations(i + 1, null, true);
      }
    };
  });
});
```

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


---

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