Just to be sure, if you load a page and let's say this page has 3 images. First refere to "/images/1.jpgn", the second to "/images/2.jpg" and the third to "/images/1.jpg" again. When the page sent to the browser, will the browser make a new request to the server and ask for the image? And if the image has already been request (like my "lets say", it has two time the same image) will it request it again or it will know that this image/url has already been loaded and will just retrieve it from the temp?
Which lead to my second question, is there a way to save with javascript/jquery this image on the computer (with the download box opening like if you were downloading a file) from the temp without having to request it again from the server?
I don't know if I am really clear but in short, I want to save an image of the page from the cache and not request a download to the server.
Browsers generally cache what they can, according to what the HTTP response headers say. That is, servers ultimately control what browsers can (or should) cache, so it's server configuration that usually controls such things.
This applies not only to images but all content: HTML pages, CSS, JavaScript, etc.