I have something very similar in my own local copy. First, I like to use defaults instead of reverting to null for certain things, and also to use maximums, like this:

var DEFAULT_QUERY_LIMIT = 10;
var MAX_QUERY_LIMIT = 25;
var queryLimit = req.query.limit ? _.min([req.query.limit, MAX_QUERY_LIMIT]) : DEFAULT_QUERY_LIMIT;

Also, I can't suggest using skip(x). It works fine for small collections, but once they get large it starts to degrade in performance, since it iterates over each item that it skips.

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