Not working in Firefox or IE

[brightrain]

Not working in Firefox or IE

[brightrain]

I believe I have worked this out and will document in case anyone else has this issue.

IE simply doesn't support the download attribute which is what is used here.
http://caniuse.com/#feat=download

Firefox required that I insert the anchor link into the dom before it would fire the download. Perhaps there's a more elegant solution but adding this to the download function before triggering the click event worked for me (not setting text ensures it isn't visible):

a.href = img.getAttribute('src');
// added this line
document.getElementById("idOfElement").appendChild(a);
a.click();

[krunkosaurus]

Thanks @brightrain. I've added support for this Firefox workaround in the latest code. I don't have an IE machine on hand to test, but will take a look when I do.