With javascript, how do you get final result URL after 302 redirect on img src?

Question

If there is an img tag in a page whose final image it displays comes after a 302 redirect, is there a way with javascript to obtain what that final URL is after the redirect

Answer 1

Here is a workaround that I found out. But it works only if the image on the same domain otherwise you will get an empty string:

var img = document.getElementById("img");

getSrc(img.getAttribute("src"), function (realSrc) {
    alert("Real src is: " + realSrc);
});

function getSrc(src, cb) {
    var iframe = document.createElement("iframe"),
        b = document.getElementsByTagName("body")[0];

    iframe.src =  src;
    iframe.className = "hidden";
    iframe.onload = function () {
        var val;

        try {
            val = this.contentWindow.location.href;
        } catch (e) {
            val = "";
        }

        if (cb) {
            cb(val);
        }


        b.removeChild(this);
    };

    b.appendChild(iframe);
}

http://jsfiddle.net/infous/53Layyhg/1/