I developed an add-on, daneshLink, which was verified by Firefox. Users installed this add-on and used it. This add-on worked, but when Firefox updated to version 50.0, this add-on doesn't work.
(Note: Add-on was not removed or disabled after updating Firefox. It just doesn't work at all).
var x = content.document.getElementsByTagName('html')[0].innerHTML;
var test = x.match(/>article Id:[0-9a-zA-z]/img);
var url = "> <a href=\"http://mysite.ir/index.jsp?articleID=";
for (var i = 0; i < test.length; i++) {
x = x.replace(test[i], url +">Download :" + test[i] + "</a>");
}
content.document.getElementsByTagName('html')[0].innerHTML = x;