occasionally useful » scripts

Accessing GM_xmlhttprequest from event handlers bound by jQuery

Max — Fri, 02 Jan 2009 05:42:05 +0000

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.

Google Reader Commenter script

Max — Thu, 01 Jan 2009 23:55:18 +0000

At Esther's request, I wrote a script that lets you comment on blogs that are in your Google Reader list. Right now it only works on Blogger and WordPress blogs, but that's actually a fair number of blogs.

Requirements: Firefox, Greasemonkey Plugin

Check it out here: GitHub repository

Here's a picture: Picture

spud! greasemonkey script

Max — Fri, 11 Jul 2008 07:04:31 +0000

I've dabbled a little in Greasemonkey, but I've yet to be inspired enough to publish something I've made. Well, I'm tempted to do so now -- it's a script to alter your experience a bit with spud!'s pages.

Feature 1) You know how it says Local, which really means <500 miles? What if you don't think that's really all that local? Isn't it a hassle to click on a bunch of links that generate popups to see how far away something actually is? I thought so too, which is why I have the following feature:

In other words, it inserts a link that, upon being clicked, will reveal in a fraction of a second how far the product actually came. I'm requiring the user to click because otherwise you have like 4 dozen AJAX requests every time you load the page -- not nice for you, spud!, or your ISP.

Feature 2) Price per unit calculations.

Before:

After:

As you can see, it calculates the price per ounce in these two cases. The calculations don't work across the entire website because spud! isn't that consistent, but it should work in the most common cases.

Feature 3) The third and final feature is a link that omits any entries on the page that are not local (by spud!'s standards). I'm not going to include a picture because it's not that interesting. If you want to give it a try, click here. You need a recent version of Greasemonkey installed.