Set.prototype.difference()

The difference() method of Set instances takes a set and returns a new set containing elements in this set but not in the given set.

A∖B={x∊A∣x∉B}Asetminus B = \{xin Amid xnotin B\}

!A Venn diagram where two circles overlap. The difference of A and B is the part of A that is not overlapping B.

difference() accepts set-like objects as the other parameter. It requires this to be an actual Set instance, because it directly retrieves the underlying data stored in this without invoking any user code. Then, its behavior depends on the sizes of this and other:

Syntax example: difference(other)