Blazor component

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Basic component

Components/MyComponent.razor
<h1>Test</h1>
<p>@ChildContent</p>
Components/MyComponent.razor.cs
public partial class MyComponent : ComponentBase
{
    [Parameter]
    public RenderFragment ChildContent { get; set; }
}
Components/MyComponent.razor.css
h1 {
    color: coral;
}
Pages/Index.razor
@page "/"
@using Component.Components

<MyComponent>
    test !!!
</MyComponent>

Callback event

Components/MyComponent.razor.cs
[Parameter]
public EventCallback<string> Callback { get; set; }

private string description;

private async Task UpdateDescription()
{
    await Callback.InvokeAsync(description);
}
Pages/Index.razor
<MyComponent Callback="MyComponentCallback" />

@code {
    void MyComponentCallback(string description)
    {

    }
}

Binding with component parameters

Components/MyComponent.razor.cs
[Parameter]
public string Description { get; set; }

// name of the EventCallback has to be [PropertyName]Changed
[Parameter]
public EventCallback<string> DescriptionChanged { get; set; }

private async Task UpdateDescription()
{
    await DescriptionChanged.InvokeAsync(description);
}
Pages/Index.razor
@* two ways binding of the component parameter Description with the local field description *@
<MyComponent @bind-Description="description" />

@code {
    private string description = "Text";
}

Cascading values and parameters

Set a value for the component hierarchy from an ancestor component to any number of descendent components.

Pages/Index.razor
@* BtnStyle will be available in MyComponent and all its descendent components *@
<CascadingValue Value="BtnStyle">
    <MyComponent />
</CascadingValue>

@code {
    string BtnStyle = "btn-success";
}
Components/MyComponent.razor.cs
[CascadingParameter]
public string BtnStyle { get; set; }