How to prevent a default action of a link/anchor tag and perform a custom action when the link is clicked?

You can call the preventDefault action in onclick event of an anchor tag. Refer to the following code sample to prevent opening a link when the link is clicked.

<a href="https://www.syncfusion.com/" target="_blank" @onclick:preventDefault>Syncfusion</a>

This feature was made available from .NET Core 3.1 Preview 2 for Blazor.

You can also perform custom action for onclick in the anchor tag by defining the same onclick event and mapping it to custom action.

<a href="https://www.syncfusion.com/" target="_blank" @onclick:preventDefault  @onclick="@OnClick">Syncfusion</a>
@code {
         public void OnClick(){
              //triggers on click
         }
}