Found this buried in my drive, honestly I don't remember how it works, but from what I can glean from the source here's what you got:

select(predicate: string, object?: object): any;

A function that takes a predicate path string, and then applies it to an object, and gives you the result. It looks like the most basic operation is just dot notation:

obj = {
	a: {
		b: {
			c: 5
		}
	}
};
select('a.b.c', obj); // => 5

And then you can evaluate more advanced predicates with brackets:

• Index obj[5]: Simple Index, get fifth element obj['key']: Normal JS Bracket Access
• Ranges obj[5:]: Get from index 5 to the end. obj[:5]: Get from the beginning to index 5. obj[2:5]: Get from index 2 to index 5. obj[2:12:2]: Get every second element from index 2 to index 12
• Expressions obj[first == true]: Get every element of obj with a key called first that has a value true. Similar for strings obj[first == 'test'] and numbers obj[first == 5] obj[first != true]: Similar to above, but not equal. obj[first < 5]: Similar to above, but less than. obj[first <= 5]: Similar to above, but less than or equal to. obj[first > 5]: Similar to above, but greater than. obj[first >= 5]: Similar to above, but greater than or equal to.
• String Expressions obj[first ^= 'abc']: Get every element of obj with a key called first that has a value that starts with 'abc'. obj[first $= 'abc']: Same as above, but ends with. obj[first *= 'abc']: Same as above, but contains.

Predicates can also match against other predicates

obj[first != second]

Predicates look like they can be nested, and there are logical operators, so you can do stuff like:

obj[first == 2 && (second != 3 || third == 'value')]

It also looks like binary operators +, -, *, /, % are supported, and either operand can be a predicate on it's own.

obj[first <= (2 + second.numberValue)]