Summary

In this chapter, you learned about comparing collections. In Immutable.js applications, you can't always rely on simple equality with collections. Part of the collection might be equal to part of another collection, or you might want to compare more than two collections. The two main techniques that you learned were intersections and differences.

You implemented set intersections and differences using set methods. You then implemented the more involved intersection and difference functionality with lists. Then you implemented the intersection and difference functionality for maps.

In the following chapter, we'll look at ways that collections can be combined.