if you update the data source, you will need to rebind the grid in order to see the new changes rendered. Otherwise you need to use KnockoutJS, we have integration for it as CTP in 2012.1. In that case only the updated cells will be re-rendered, which is a lot better in terms of performance. you can find KnockoutJS samples with the igGrid here:

http://samples.infragistics.com/jquery/grid/grid-knockoutjs-integration

Hope it helps. Thanks,

Angel 

Second, restoring the vertical scroll position when any form of virtualization (fixed or continuous) is damn tricky and I'm afraid that there's no simple solution for that.
Yes, the igGrid has a public API method called virtualScrollTo(), but it's not meant to be used to solve this particular problem/request.

Other forum members have struggled with this and I would like to give you the links to the particular thread(s) where my colleague, Martin Pavlov answered (and I back him up on this) that unfortunately there is no simple way of doing this without actually modifying the code of the igGrid that's responsible for virtualization.
(sorry - with the revamp of the forum UI I can't find the forum thread(s) where this was discussed :( )

There's a product idea submitted about making the virtualScrollTo() method a viable piece of achieving the desired outcome. You can submit it once again if you wish, but I'm afraid that that won't change much - our developers are looking into product ideas and development requests based on priority so this will be implemented once it moves up their queue.

Ian Fletcher said:

Also if I know I have only updated a single record in my local JSON array do I need to rebind the entire dataset or is there a way I can just tell the grid to upadet a single row?

1. Use the updateRow() API method of the igGrid's Updating feature so that the grid can also be notified of the change
2. Configure the grid to use the KnockoutJS framework (we've got a sample demoing that) - this will require you to learn some KnockoutJS, write the necessary KnockoutJS-related JS object artifacts and configure the grid in a KnockoutJS-understandable manner, but you will then receive the desired outcome and a nice MVVM for the grid
3. Yep, call dataBind() on the grid - that's rebind the grid to the data and then cause the grid to re-render

Hope you can take advantage of #1 or #2 - I think that they are the cleanest ones.

Cheers!
Borislav 

And I'm not even from the customer support team :D
(the guys there rock as well ;-))

If you're having problems with calling updateRow and getting the desired results, I'd say it's either a mis-configuration issue or a bug (specific to the scenario) - I ought to know since testing the Updating feature is one of my responsibilities :).

If I may suggest, why don't you try calling the updateRow method on some of the editing-related samples that we have?
(just use the JS console of your browser without any worries) 

If that doesn't work for you, please provide us with a description (or code) of your scenario and if possible - a working sample with dummy data.
(that'll help us demystify the issue in a jiff)

Cheers!
Bobby