Conditional Scroller

[bdichiara]

I am having the hardest time trying to write a condition for scrolling in an AJAX chat app i'm writing. After the AJAX request that updates the log, i'm using

objDiv.scrollTop = objDiv.scrollHeight;

I was trying to write a condition so if the user decides to scroll up to read older text, that it will not scroll them to the bottom until they are finished and scroll back down themselves. When doing this, i ran into a couple of issues. So, here's what I'm looking to do:
1. when the chat is initialized, i want it to perform the scroll function (above). It's possible that there already be messages in the window, so start them at the bottom.
2. if they are within 20px (or 30) from the bottom, then scroll them on down the rest of the way

There may be a better way to do this, if anyone has any suggestions. Otherwise i guess a series of conditions will help it behave normally.

Thanks.

[bdichiara]

Ok, i think i got this figured out:

var initialized = false;

... then inside the function ...

var objDiv = document.getElementById("message_window");
var sHeight = objDiv.scrollHeight;
var sTop = objDiv.scrollTop;
var mHeight = objDiv.clientHeight;
if(initialized){
	if((sTop+mHeight) >= (sHeight-30) && (sHeight > (mHeight+25))){
		objDiv.scrollTop = objDiv.scrollHeight;
	}
} else {
	var theDiv = document.getElementById("message_window");
	theDiv.scrollTop = theDiv.scrollHeight;
	initialized = true;
}