Dot notation is a cool feature of mongodb that lets you set nested properties of an object. It's not hard to support this in your own JavaScript code. Here's the _get method I use in the joinr npm module to allow access to sub-properties of 'o' via syntax like 'name.last'. Also works for arrays. And if you pass a function, that function is calle…

dotNotation.js

  // This supports: foo, foo.bar, foo.bar.baz (dot notation,
  // like mongodb) and also passing in a custom accessor function

  _get: function(o, accessor) {
    var fn = accessor;
    if (typeof(accessor) === 'string') {
      fn = function(o) {
        var keys = accessor.split(/\./);
        _.each(keys, function(key) {
          o = o[key];
        });
        return o;
      };
    }
    return fn(o);
  }

This is quite useful for a problem I'm working on. Now I wonder how hard mimicking the positional $ would be...