'use strict';

const union = (s1, s2) => new Set([...s1, ...s2]);

const intersection = (s1, s2) => new Set(

[...s1].filter((v) => s2.has(v))

);

const difference = (s1, s2) => new Set(

[...s1].filter((v) => !s2.has(v))

);

const complement = (s1, s2) => difference(s2, s1);

// Usage

const cities1 = new Set(['Beijing', 'Kiev']);

const cities2 = new Set(['Kiev', 'London', 'Baghdad']);

const operations = [union, intersection, difference, complement];

const results = operations.map((operation) => ({

[operation.name]: operation(cities1, cities2)

}));

console.dir({ cities1, cities2 });

console.dir(results);