jQuery Cross-Site AJAX Plugin
April 12th, 2007 by Ralf S. EngelschallIt is well known that with the help of a dynamically generated XHTML <script> DOM element one can achieve a portable cross-site variation of an AJAX-style client-server communication as the <script> is not staying under the “same-origin security policy” which restricts the regular AJAX methods. This allows one to load code from a third-party URL in the background.
For this in JavaScript one generates a <script> DOM element with a type attribute set to text/javascript and a src attribute set to the URL of the third-partly URL. That’s it. Well, more or less. But as a jQuery user I wanted this functionality abstracted with a variation of the already existing (plain AJAX) jQuery.getScript() function, which in turn especially allows me to execute a callback function once the script is loaded. And for cleanup and memory leak prevention reasons I wanted that the dynamically generated <script> DOM node is garbage collected automatically, too.
My result is a small jQuery plugin jquery.xsajax.js which provides just this. Find this jQuery plugin in the File Repository area.
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April 12th, 2007 at 16:02 |
That plugin doesn’t work in Safari. It looks like you lifted the logic from the jQuery library because I hit a similar problem.
The reason it doesn’t work in Safari is because the script element doesn’t fire any events when the external library is loaded, and hence listening for the onreadystatechange doesn’t work.
I wrote an entry on how to get around this problem, but I’m not sure it will be helpful to your plugin without replicating the core test:
http://remysharp.com/2007/04/12/how-to-detect-when-an-external-library-has-loaded/
April 12th, 2007 at 17:15 |
Remy Sharp: yes, I had to apply the MSIE special case first and then determined that jQuery core contains a similar thing. And hence I’ve taken over the Safari special case blindly, because I’ve no Safari at hand myself. I’ll look at your workaround. Thanks for the hint.
April 12th, 2007 at 17:17 |
BTW, does anybody know whether Konqueror/KHTML and Safari/WebKit emit any(!) event at all after loading a <script>?
April 12th, 2007 at 18:02 |
Ok, I’ve looked deeper into the WebKit sources and the source WebKit/WebCore/html/HTMLTokenizer.cpp shows in the function HTMLTokenizer::notifyFinished() an explicit code which seems to emit the “load” event for the <script> tag. And this line exists already since a longer time in WebKit. So, as long as one uses a not too ancient Safari, I would expect that the “load” event on a <script> fires just fine.
Unfortunately I’ve no Safari available myself, so can someone with a recent Safari please go to…
http://trainofthoughts.org/repo/export/jquery/jquery.xsajax.test.html
…and see whether you see the expected output…
…occurs. If you only see the first two lines, we still have a problem with Safari. If the last two lines also are visible it means the “load” event fired just fine in Safari.
April 13th, 2007 at 9:37 |
Ok, in the latest version of jquery.xsajax.js I’ve now tried to apply a Safari specific workaround based on two <script> tags. Perhaps someone with Safari can run http://trainofthoughts.org/repo/export/jquery/jquery.xsajax.test.html and tell me what output sequence (”N. xxxxx, N. xxxx”) is visible.
April 13th, 2007 at 15:38 |
According to responses on jquery-discuss the plugin now also should work in Safari.
April 19th, 2007 at 22:14 |
This is a really interesting plugin. I have been a long time JSAN user http://openjsan.org/doc/c/cw/cwest/JSAN/0.10/lib/JSAN.html and yesterday saw the videos of John Resig on yahoo. So this morning I tried jquery for the first time and within an hour had trimmed many of my core functions down to 1/3 their original size. But I was still lacking the On-Demand Javascript http://ajaxpatterns.org/On-Demand_Javascript and lazy loading I am so used to. Instead of using jquery and jsan seperately i was curious how well the two could be integrated. I found a couple require plugins, but they load async which is not so great for lazy loading, they also lack the namespace aspect that jsan provides.
I took a quick crack at replicating jsan.use and came up w/:
(function(jq){ jq.extend({ jsanUse: function(pkg, o){ o = jq.extend({ includePath: ['/jslib','jslib'], altURL: null, min: false }, o || {}); if(o.altURL == null){ path = pkg.replace(/\./g, '/'); path = (o.min)?path.concat('-min.js'):path.concat('.js'); }else{ path = o.altURL; } try { classdef = eval(pkg); if (typeof classdef != 'undefined') return classdef; } catch (e) { /* nice try, eh? */ } for (var i = 0; i ...May 28th, 2007 at 17:50 |
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Hi,
The picture of yourself hides the links in the menu (Firefox v2.0.0.3) … is there no way to set you to :invisible? ;)
The Cursor is somehow :invisible in this comment textarea, after typing some letters …
djot
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October 26th, 2007 at 22:34 |
Clever workaround, but in my tests under Safari, there is no guarantee that scripts will be loaded in the order they are created within the DOM. See my test case here:
http://xorox.net/trax/jsloadtest.html
Expected output for sequential execution would be 1,2,3,4 but Safari 413.2 shows 3,1,2,4.
November 13th, 2007 at 7:05 |
Is there any solution for getting *HTML content* from other cross-site url?
August 8th, 2008 at 20:02 |
Hi!!
is it freely available?? how can i download the js file?? the svn client asks me for username and password.
Regards,
August 8th, 2008 at 20:21 |
It can be downloaded directly from the SVN web frontend: http://trainofthoughts.org/repo/getfile?f=jquery/jquery.xsajax.js&v=35
August 9th, 2008 at 16:52 |
Thanks :)