AJAX and the Dynamic Script Tag

I didn’t know that javascript can be made to execute requests to sites that didn’t originate from the original server. Jason Levitt details this technique at XML.com:

if you make web services requests using the dynamic script tag approach — and the web service lets you specify a JavaScript callback function — you can have unfettered access to the web service in a seamless, cross-domain, cross-browser fashion.

Confused? Here are the steps:

1. The server is designed to respond to the following request.

http://www.test.com/test.php?functionname=myfunction&param1=aaa&param2=bbb

With the following:

myfunction({'Value1': 'foo1', 'Value2': 'foo2'})

2. Next you take the results and write it into a script tag to execute it.

<script>
  function myfunction(params)
  {
     alert (params['Value1']);
  }
</script>
<script>
   myfunction(({'Value1': 'foo1', 'Value2': 'foo2'});
</script>

Via Stuart Holoway