I was searching for a sorted map in javascript and found collections.js's implementation - SortedMap. I also see that they have something called SortedArrayMap.
In the description of SortedArrayMap it says:
A map of key value pairs, sorted by key, backed by an array.
(Source)
And in the description of SortedMap it says:
A map with entries sorted by key.
What exactly does backed by an array mean? and what is the difference between it and the normal SortedMap?
At first glance, SortedArrayMap uses a binary search strategy to maintain the order of the entries and is backed by an array, which means that use an array as a basic data structure(to maintain data of key). So that means in the end, that it uses a map based on SortedArray class.
However, SortedMap is a general key/value collection, where you can access values with their relative key(quick access rather than an array order).
Anyway, if you want to dive a bit more into this topic, you can find a very good explanation on the is the official website of collections.js,
As stated on http://www.collectionsjs.com/map, maps are different as they work like dictionaries but accepting even objects as a key.
Reading the Dict documentation on http://www.collectionsjs.com/dict we understand that:
A dictionary is a specialized map. The keys are required to be strings.
An array is simply a data structure where you can insert anything using a simple push(thingToInsert). Items inserted into an Array are just values without a key to point to them.
