How to hash server side?

[qodesmith]

I like the idea of having hashes stored in my database for images so I could send that to the client to show a blurred image first while the full image is being rendered. How does one do this on the server? The TypeScript examples show loading an image using the Image constructor, and later setting its src to a url. This would imply a fetch call. Is there no programmatic way to read an image file's binary data and generate a hash from that?