When rendering any mark-up, it is possible to assign standard JavaScript events on the rendered HTML elements so that our own Blazor C# methods are executed. For example, we have used the @onclick Directive in many samples elsewhere:

<button @onclick=ButtonClicked>Click me</button>

These event directives have full IntelliSense support within the Visual Studio editor, so starting to type the @ symbol should present us with a comprehensive list of available directives, along with a description identifying which argument class type the event passes us in our event handler. DOM events start with @on.

Sets the '@onabort' attribute to the provided string or delegate value. A delegate value should be of type 'Microsoft.AspNetCore.Components.Web.ProgressEventArgs'

Warning: When writing a Blazor app that runs entirely on the server, Blazor will hook events in the browser and send them to server so our C# methods can be invoked. This can lead to a noticeable slow-down for frequently fired events such as onmousemove.

Note: Because JavaScript invocation of C# methods is asynchronous, this means that in C# methods we cannot cancel events as we can in JavaScript. This is because cancelling browser DOM events is a synchronous operation, by the time our C# has been asynchronously invoked it is already too late to cancel the event.

Available DOM events and their parameter types include: