Handle Client-Side Events in the Blazor Document Viewer

• Feb 09, 2026
• 3 minutes to read

The Blazor Document Viewer is based on the DevExpress Web Document Viewer. The Web Document Viewer includes an advanced client-side API that allows you to customize UI elements and behavior. The DxDocumentViewerCallbacks component exposes properties that allow you to specify JavaScript functions (client-side event handlers).

Follow these steps to customize the Blazor Document Viewer using its client-side API:

1. Place your JavaScript code in a separate file in the wwwroot folder. Use the window object to create a namespace for your code.

2. Use the DxResourceManager.RegisterScripts() method to register the corresponding script:

3. Specify JavaScript function names as event handlers for the DxDocumentViewerCallbacks component:

Document Viewer Client-Side events allow you to perform the following actions:

Customize Document Viewer Elements (Toolbar, Panel, Export Options)

Event	Description
CustomizeElements	Allows you to customize the Web Document Viewer’s UI elements (Parameter Panel, Right Panel, Toolbar).
CustomizeMenuActions	Enables you to customize the Web Document Viewer’s toolbar.
CustomizeExportOptions	Allows you to customize the Web Document Viewer’s available export formats and corresponding export options.

Customize Parameter Editors

Event	Description
CustomizeParameterEditors	Enables you to provide custom editors for report parameters.
CustomizeParameterLookUpSource	Allows you to customize look-up report parameter values.

Manage Report Parameters

Event	Description
ParametersInitialized	Allows you to get the client-side parameter values when they are initialized and modify them.

Respond to Parameter Reset and Submission

Event	Description
ParametersReset	Occurs after report parameter values are reset to their default values.
ParametersSubmitted	Occurs after report parameter values are submitted.

Respond to Document Loading

Event	Description
DocumentReady	Occurs after the Web Document Viewer loads a report document.

Manage Interactivity

Event	Description
PreviewClick	Occurs when a report document is clicked.
EditingFieldChanged	Occurs each time an edit field’s value changes.

Localize the Document Viewer

Event	Description
CustomizeLocalization	Enables you to replace the Web Document Viewer’s localization strings with custom strings.

Respond to Server-Side Errors

Event	Description
OnServerError	Occurs on the client each time a server-side error is raised.

Initialize the Document Viewer

Event	Description
BeforeRender	Occurs before the Web Document Viewer UI is initialized.
OnInitializing	Occurs before the View Model is fetched from the server, and before the BeforeRender event.

See Also

Tasks and Solutions for ASP.NET Core Applications