JS Data Structures — Maps and Sets
The way, in which data is structured, plays a vital role in being able to efficiently perform certain operations on the data or solve certain problems in relation to the data. For example you can delete any item from a doubly linked list in constant time, whereas that could take linear time if the list is represented as an array. Also, searching for the presence of a key in an array of keys can be done more efficiently (in logarithmic time) when the array is sorted than when not sorted.
Prior to the ECMAScript 2015 specification updates (_