Added: jquery/jquery.xsajax.html =================================================================== --- jquery/jquery.xsajax.html (rev 0) +++ jquery/jquery.xsajax.html 2007-04-13 14:39:58 UTC (rev 36) @@ -0,0 +1,82 @@ + + + + jQuery XS AJAX Plugin + + +

jQuery XS AJAX Plugin

+ +

Description

+ + It is well known that with the help of a dynamically generated + DOM node corresponding to a XHTML <script> + element one can achieve a portable cross-site (XS) variation + of an AJAX-style client-server communication as the + <script> element is not staying under the + "same-origin security policy" which restricts all the regular + AJAX methods. This allows one to asynchronously load JavaScript + code from a third-party URL. + +

+ The JavaScript code in jquery.xsajax.js is a jQuery plugin, providing an + abstraction layer for this functionality by resembling the + standard AJAX-based jQuery.getScript(url, callback) function with a + companion jQuery.getScriptXS(url, callback) function. + +

+ Notice 1: the point of this plugin is not the bare dynamic + generation of the <script>. The point is + that a callback function is executed once the script was + loaded and executed by the browser and that the generated + <script> is automatically garbage collected from + the DOM again afterwards. + +

+ Notice 2: the possibility to load a JavaScript file from a + sibling but third-party URL is also of great interest when + one wishes to set cookies for the third-party URLs. Suppose + you have three websites www.example.com, www.example.net and + www.example.org and on www.example.com/login you have your + customer login form. Once the customer was authenticated, + a cookie containing a "certificate" should be set. Setting + this for ".example.com" is trivial, but how do you at the + same time set it for all three domains? The solution is + this: www.example.com/login uses jQuery.getScriptXS() to + send the issued "certificate" via a query string to both + www.example.net/reflector and www.example.org/reflector. + Behind those URLs a small CGI just converts the "certificate" + in the query string into a corresponding HTTP response cookie + (now for its own domain!) and returns even a possibly empty + JavaScript script. Once www.example.com/login has received the + two final notification (via the callback function) that both + scripts were loaded, it knows that the two third-party cookies + were set and can proceed by forwarding to the next page in + sequence. Last hint: keep P3P in mind for MSIE when setting + the cookie in the HTTP response ;-) + +

Example

+ +

http://www.example.com/test.html:
+

+            <script type="text/javascript">
+               jQuery.$foo = "bar";
+               alert("jQuery.$foo="+jQuery.$foo);
+               jQuery.getScriptXS(
+                   "http://www.example.net/test.js",
+                   function () { alert("jQuery.$foo="+jQuery.$foo); }
+               );
+            </script>
+

http://www.example.net/test.js
+

+              jQuery.$foo = "quux";
+

+ +