The previous section focused on collections and how to map them. But wait, objects are collections too, right? That is indeed correct, but it's worth differentiating between arrays and plain objects. The main reason is that there are implications with ordering and keys when performing map/reduce. At the end of the day, arrays and objects serve different use cases with map/reduce, and this chapter tries to acknowledge these differences.

Now we'll start looking at some techniques Lo-Dash programmers employ when working with objects and mapping them to collections. There are a number of factors to consider, such as the keys within an object, and calling methods on objects. We'll take a look at the relationship between key-value pairs and how they can be used in a mapping context.