Is there a technique for finding JsVar memory leaks?

I'm not sure if this is of the help you are looking for to solve your problem... Automatic/hidden memory managment has come a long way and should become transparent to the 'user'. If memory leaks occur is to me an indication that the APIs are not clearly classified, and components that straddle both worlds - the automatic and self-managed world - are not properly implemented. Keeping the straddling components to a minimum and as simple and small as possible help to localize the issues. Localize not only in the sense of 'finding out' but also 'limit to a local impact'... which allow a narrow testing.