Javascript client lazy-loading models from ASP.NET MVC backend
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I'm developing a rich client web application which deals with a large volume of information. After a few stumbling blocks coming up with an application architecture, I've boiled down the following list of requirements:

* I need a javascript repository which can pull data from an ASP.NET MVC3 backend.
* I need to lazy-load or fetch-load specific properties of repository entities.

Is there a Javascript library that can do some or all of this - especially the lazy loading?