Assuming you are using client side javascript, you need to call either GET or HEAD on the file you want the date from, and than pull the date out of the response.

Nowhere becomes this more apparent than in aspects like JavaScript’s brilliantly designed Date class, which astounds people to this day with its elegant handling of JavaScript’s powerful type ...

The JavaScript function I called from my Blazor method is in my project's Index.html file under the project's wwwroot node. The function accepts the DotNetObjectRef that's wrapping the Customer object ...