Set.prototype.union()

The union() method of Set instances takes a set and returns a new set containing elements which are in either or both of this set and the given set.

A∪B={x∣x∊A or x∊B}Acup B = \{xmid xin Atext{ or }xin B\}

!A Venn diagram where two circles overlap. The union of A and B is the region contained by either or both circles.

union() 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, it iterates over other by calling its keys() method, and constructs a new set with all elements in this, followed by all elements in other that are not present in this.

Syntax example: union(other)