Image caching API, imageUrl option for preCaching

Continuing the discussion from httpClient method HEAD:

Instead of doing serverside httpClient.requests to preCache images, it would be nice to have a js api to do it.
And perhaps a method to check whether an imageUrl has been cached.
Perhaps a method to list cache, size of cache, clearCache, delete item, etc…

Another way to preCache could be for imageUrl to have an option to trigger preCaching…

I guess your real problem is that it takes too long to generate some of these images? So the best fix is speeding up the image generation on our side?