addOr

addOr(target, value, or)

Adds a value to the target set and returns a new set. If the value already exists in the set, returns the or value instead.

data-first

addOr(new Set([1, 2]), 3, null); // Set([1, 2, 3])
addOr(new Set([1, 2]), 2, null); // null

data-last

pipe(new Set([1, 2]), addOr(3, null)); // Set([1, 2, 3])
pipe(new Set([1, 2]), addOr(2, null)); // null