Mastering Immutable.js

Searching sorted collections

The main reason that you would want to change the search direction is if the collection in question is sorted. For example, you want to find the oldest person in a list, or you want to filter the five oldest people in your list by some other criteria. It doesn't make sense to start at the beginning of the list if it's sorted in ascending order. You could reverse the list and then filter, but reversing a collection isn't free in terms of performance.