Synchronuos server callback in a standard way

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Subject: Synchronuos server callback in a standard way
Posted by:  Andrus (
Date: Sun, 13 Jul 2003

User enters an item code to a browser <input type=text> field.
I need to verify the code entered using server callback.

If item code is wrong, user is not allowed to leave the field.
So I think I must use synchronuous server callback for this. Data passed to
server is larger tham 2KB, so POST method should be used.

Unfortunately, W3C standard does not support synchrunuous server callbacks.
It allows using <iframe src=> trick or <script src=>  trick by changing src=
attribute dynamically.
Both of them are asynchronous.

IE has Microsoft.XMLHTTP  object and Mozilla its clone, XMLHttpRequest()
function. However, those non-standard extensions will not work in other

It it possible to make synchronuous server callbacks in a standard way ?