Adds a new thing to the set and returns the number of things which are actually added to the set. For example my_set.add(#42); will return 0 if my_set already contains thing #42.

This function generates a change (except when called on a variable).


set.add(thing1, thing1, ..., thingX)

Return value

Returns the number of things which are added to the set.


This code adds things to a set:

s = set();
a = {item: 'a'};
b = {item: 'b'};

// add both `a` and `b` to set `s`; note that `a` is only added once;
s.add(a, a, b);

Return value in JSON format