In this section, we will turn our attention to reducing objects and working with object accumulators. Reducing objects is a lot like reducing arrays, the difference being that you have a key instead of an index. Oh yeah, there's also the ordering, which is kind of important—arrays are ordered, objects aren't.
Previously in the chapter, we caught a glimpse of what accumulators are. Here we'll take a deeper look at object accumulators, including some of the built-in Lo-Dash functions that utilize this concept.
You can reduce an object to something different based solely on its keys. For example, if there are only certain properties you need, you can reduce the object to include only those properties, using the following code:
var object = {
first: 'Kerry',
last: 'Singleton',
age: 41
},
allowed = [ 'first', 'last' ];
_.reduce(object, function(result, value, key) {
if (_.contains(allowed, key)) {
result[key] = value;...