FileUpload

@inherits ControlComponent
<p>Select a file to upload:</p>

<asp.FileUpload @ref="this.fileUpload">
</asp.FileUpload>

<br />
<br />

<asp.Button Text="Upload file"
                                            OnClick="this.UploadButton_Click">
</asp.Button>

<br />

<asp.Label @ref="this.uploadStatusLabel">
</asp.Label>

@code {
                                            private FileUpload fileUpload;
                                            private Label uploadStatusLabel;

                                            protected void UploadButton_Click(object sender, EventArgs e)
    {
                                            // Before attempting to perform operations
                                            // on the file, verify that the FileUpload
                                            // control contains a file.
                                            if (fileUpload.HasFile)
        {
                                            // Get the name of the file to upload.
                                            string fileName = fileUpload.FileName;
                                            // Get the size in bytes of the file to upload.
                                            int fileSize = fileUpload.PostedFile.ContentLength;
                                            // Get the extension of the uploaded file.
                                            string extension = System.IO.Path.GetExtension(fileName);
                                            // Notify the user of the name of the file
                                            // was saved under.
            uploadStatusLabel.Text = "Your file was saved as " + fileName
                + " ( fileSize:" + fileSize + " extension:" + extension + " )";
        }
                                            else
        {
                                            // Notify the user that a file was not uploaded.
            uploadStatusLabel.Text = "You did not specify a file to upload.";
        }
    }
}

@inherits ControlComponent
<p>Select an image file:</p>

<asp.FileUpload @ref="this.fileUpload" AutoPostBack="true"
                                            OnPostedFileChanged="this.FileUpload_PostedFileChanged"></asp.FileUpload>

<br />
<br />

<asp.Image @ref="this.image" Visible="false"></asp.Image>

@code {
                                            private FileUpload fileUpload;
                                            private Image image;

                                            protected void FileUpload_PostedFileChanged(object sender, EventArgs e)
    {
                                            this.InvokeWaitTask(async () =>
        {
                                            if (fileUpload.HasFile)
            {
                                            // Save the file to client ObjectURL.
                                            string imageUrl = await fileUpload.SaveAsUrlAsync();
                                            // Show image.
                image.ImageUrl = imageUrl;
                image.Visible = true;
            }
        });
    }
}