blazor_inject.cs

[Layout(typeof(MainLayout)), Route("/counter")]
public class Counter : BlazorComponent
{
    private int currentCount = 0;

    protected override void BuildRenderTree(...)
    {
        ...
        builder.AddContent(4, "Current count: ");
        builder.AddContent(5, (int) this.currentCount);
        ...
        builder.OpenElement(7, "button");
        builder.AddAttribute(8, base.onclick(
            new Action(this, this.IncrementCount)
        ));
        builder.AddContent(9, "Click me");
        ...
    }

    private void IncrementCount()
    {
        this.currentCount++;
    }
}