Is it an actual best practice?

By adding a method directly into a constructor, the method is copied every time you create a new instance.
That's why it's better to add it using

Ship.prototype.isWorthIt = function(){}

outside the constructor, or by using ES6 classes.

Thanks, I've just written another one
(http://www.codewars.com/kata/reviews/553a849a1e039956bc00013c/groups/56b60c27e3a3a75770001032)

If "name" is null, it would cause a NullPointerException, null doesn't has "isEmpty()" method. You're just validating if the String happens to be equals to "".

Nice, I suppose :3