asp.net Protected Function Return value

Hi,
I've seen a blog article where this method was used to execute a javascript function but I didn't think that was possible serverside.  The way it was explained was there is a public sub in the codebehind that executes the Protected Function.  The public sub is fired by a clientside onclick event. 
The author then shows the return value of the protected function in the vb.net code behind assigned like this:
return string.format("myJavascriptFunction(['object', '{0}', '{1}']);", link1, link2) That returns undefined in my application, am I totally missing something here?
thanks.
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