How can one generate and save a file client side using Blazor?

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Creator of Blazor Steve Sanderson used JavaScript interop for similar task during one of his last presentations.

You can find example on BlazorExcelSpreadsheet

Solution includes three parts:

1) JavaScript

function saveAsFile(filename, bytesBase64) {
        var link = document.createElement('a');
        link.download = filename;
        link.href = "https://stackoverflow.com/questions/52683706/data:application/octet-stream;base64," + bytesBase64;
        document.body.appendChild(link); // Needed for Firefox
        link.click();
        document.body.removeChild(link);
    }

2) C# interop wrapper

public static class FileUtil
{
    public async static Task SaveAs(IJSRuntime js, string filename, byte[] data)
    {
        await js.InvokeAsync<object>(
            "saveAsFile",
            filename,
            Convert.ToBase64String(data));
    }            
}

3) Call from your component

@inject IJSRuntime js
@functions {
    void DownloadFile() {
        var text = "Hello, world!";
        var bytes = System.Text.Encoding.UTF8.GetBytes(text);
        FileUtil.SaveAs(js, "HelloWorld.txt", bytes);
    }
}

You can see it an action in Blazor Fiddle

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