Yes, see www.jsviews.com/#iftag.
In fact you can write {{if pathOrExpr}}
where path can be any combination of 'data paths' and reqular javascript operators etc.
The example shows {{if members && members.length}}
and similarly you can do all the expected conditional expressions such as:
address.zip === '88888'
, or:
foo.count < 3 && foo.total >= bar.total
,
etc. etc.