The mode is the number that appears in a list the highest number of times. There can be multiple modes in a list: in the event of a tie, this algorithm will return the most recently seen mode.

modeFast uses a Map object to keep track of the mode, instead of the approach used with mode, a sorted array. As a result, it is faster than mode and supports any data type that can be compared with ==. It also requires a JavaScript environment with support for Map, and will throw an error if Map is not available.

This is a measure of central tendency: a method of finding a typical or central value of a set of numbers.