occasionally useful ruby, ubuntu, etc

Accessing GM_xmlhttprequest from event handlers bound by jQuery

So I like jQuery. And I like Greasemonkey. I especially like the ability of Greasemonkey's ajax calls to go cross-domain. But how do I get access to this functionality in my event handlers? Calling GM_xmlhttprequest in a method that doesn't execute while the Greasemonkey sandbox is still alive doesn't work. At first I didn't think it was possible, but I discovered a way...using setInterval.

So here's the problem. You want something like this:

$(function(){
  $("a").click(function(){
    GM_xmlhttprequest({url: "http://www.google.com/", method: 'GET'});
  });
});

or something, right? But that doesn't work because by the time the $'s DOM ready event fired, Greasemonkey is gone. So what do you do? Well...keep Greasemonkey around, but in a limited capacity. Okay okay, here's the code:

var ajaxQueue = [];
var processAjaxQueue = function(){
  if (ajaxQueue.length > 0) {
    for (ajax in ajaxQueue) {
      var obj = ajaxQueue[ajax];
      // http://diveintogreasemonkey.org/api/gm_xmlhttprequest.html
      GM_xmlhttpRequest(obj);
    }
    ajaxQueue = [];
  }
}
setInterval(function(){
  processAjaxQueue();
}, 100);
 
function gmAjax(obj){
  ajaxQueue.push(obj);
}

So now you call gmAjax instead of GM_xmlhttprequest (with the same argument) and it'll get fired off within the next 100ms. Neat huh? And if you're worried about security (which you should be) -- I've tested this myself, and gmAjax isn't acccessible anywhere outside of the Greasemonkey sandbox. Huzzah, mission accomplished.