Can I get an image's file size and mime-type via JavaScript (FireFox/Gecko/Mozilla only)

问题

Can I get an image's file size and mime-type via JavaScript. I am writing a script for inspecting all images in a document. I will run the script in FireFox only so a solution specific to FireFox (undocumented/non-standard/otherwise) is perfectly acceptable. I can use jQuery if necessary.

回答1:

You could make a HEAD request with XHR which will tell you the file size, provided these images are on your domain.

回答2:

you can do it through HTTP head request

       var request;
        request = $.ajax({
                  type: "HEAD",
                  url: 'your image url',
                  success: function () {
                  alert("Size is " + request.getResponseHeader("Content-Length"));
                  alert("Type is " + request.getResponseHeader("Content-Type"));
                  }
               });

来源：https://stackoverflow.com/questions/5456245/can-i-get-an-images-file-size-and-mime-type-via-javascript-firefox-gecko-mozil