I'm not sure if you are looking to fetch the parameter from a
url that launched your application or otherwise so here are two
ways to do it . . .
From a URL use the following:
_all = ExternalInterface.call(
// This is populated from the last half of the url. It
contains everything after the ?
_queryString = ExternalInterface.call(
"window.location.search.substring", 1 );
Then you can break up _queryString by & or = or however
you want to extract the parameter.
If your trying to default a value into dateField from another
field value or a static variable use the following:
<mx:DateField text="12/31/2007"/> or