The second
parameter is the URL to request. The third parameter is a callback object. The object stores
the success and failure callback functions as well as enabling you to pass arguments into the
call to be available upon return.
var callback = {
success: myObject.processRequestSuccess,
failure: myObject.processRequestFailure,
argument: [argument1, argument2, argument3],
scope: myObject
}
You can also specify the scope that should be passed to the function calls. That way, if the
success and failure callbacks are part of a larger object, you can maintain the scope for the
this variable.
If performing a POST request, you can pass the data in with a query string format as a
fourth parameter:
var transaction = YAHOO.util.Connect.asyncRequest('POST', sUrl, callback,a
'key1=encoded+data&key2=even+more+data');
The YUI library even has a nice function to take all form fields and automatically append
them into a request (removing the need to specify the fourth parameter):
YAHOO.util.Connect.setForm(formObject);
var conn = YAHOO.util.Connect.asyncRequest('POST', 'http://example.com/', callback);
jQuery
jQuery is heavily designed around manipulating the DOM. Its Ajax approach takes the Prototype
Ajax.Updater to another level:
$('#myelement').load('/updatestatus');
As you saw in the last chapter, the $ function grabs the elements (in this case, an element
with an ID of myelement).
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