@ToiWright Hello,

I just finished your book. It is a really good book. The examples are excellent. Thank you very much.
I have a few minor comments to make, if you don't mind. I hope some of them make sense and can be useful.
I might suggest a PR for some of them if that would be helpful.

Functional point of view

• Page 92. There is no indication of how to test the Resize. To see it in action, go to the /resize web page.
• Page 98. What is the purpose of creating the interface for storage? It is not used afterwards.
  The best would be to add it as a service and then inject it on the index page. Or make a reference for chapter 6.
• Page 142. If the PWA is opened from the Windows menu, the offline page is displayed.
• Page 200. Sqlite could be proposed. It is easier to install.
• Page 203. A few words about the importance of the @key could be added.
• Page 207. Error information is never displayed on the Index page.
• Page 214. There is no information about the fact that validation will not work for subclasses. Example: Customer.Address.City.
• Page 214. Some references to validation libraries could be added. Example: Fluent Validation Library.
• Page 228. There is no error test during HTTP communication.
• Page 229. Error information is never displayed on the Index page.

Code

• Page 123. Possible improvement for the javascript to get the message when the user has denied the access to geolocation.

if (navigator.geolocation) {
    try {
        var position = await getPositionAsync();
        var coords = {
            latitude: position.coords.latitude,
            longitude: position.coords.longitude
        };
        return coords;
    }
    catch (error) {
        throw error.message;
    }
  } else {
      throw Error("Geolocation is not supported by this browser.");
  };

protected override async Task OnInitializedAsync()
{
    try
    {
        await GetPositionAsync();
        await GetForecastAsync();
    }
    catch (JSException je)
    {
        message = je.Message;
    }
    catch (Exception ex)
    {
        message = ex.Message;
    }
}

• Page 126. GetPosition could be renamed to GetPositionAsync.
• Page 130. GetForecast could be renamed to GetForecastAsync.
• Page 134. It should be in index.html for the link ... href="images/Sun-512.png" />.
• Page 168. Modification for the code : @onclick="@(() => Console.WriteLine("Blazor rocks!"))".
• Page 177. A check could be added if the delegate exists or not. if (OnDrop.HasDelegate).
• Page 182. No need for @ in the case of taskName.
• Page 182. OnClickHandler could be renamed to OnClickHandlerAsync.
• Page 202. No need in the catch to have the word Exception.
• Page 205. No need to have double parenthesis for the @ in the <span> section.
• Page 207. CheckboxChecked could be renamed to CheckboxCheckedAsync. Same for DeleteTask and AddTask.
• Page 208. Following code can be added when the task has been created.
  tasks.Where(x => x.TaskName == newTaskItem.TaskName).First().TaskItemId = task.TaskItemId;
• Page 228. HandleValidSubmit method could be renamed to HandleValidSubmitAsync.
• Page 229. No need to have a ready variable. A check can be made with expense == null.
• Page 229. No need also for ; after }.

Topics that can be added to the book

• Some words on <CascadingValue>.
• Some words on @ref.
• Some words about Container.