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Set Composition

I'll be 10000% honest, I don't often use these fancy set composition methods... but maybe I should. They're pretty neat. In most of my work I just use sets to check for existence or de-duplicate values. But, if you're versed in set theory, you might find these methods useful.

Intersection

The .intersection() method returns a new set containing the elements that are in both sets.

const heroes = new Set(["eren", "mikasa", "armin", "reiner"]);
const villains = new Set(["eren", "reiner", "bertholdt", "annie"]);
const samesies = heroes.intersection(villains);
console.log(samesies);
// Set { 'eren', 'reiner' }

Difference

The .difference() method returns a new set containing the elements that are in the first set but not in the second set.

const heroes = new Set(["eren", "mikasa", "armin", "reiner"]);
const villains = new Set(["eren", "reiner", "bertholdt", "annie"]);
const nonVillains = heroes.difference(villains);
console.log(nonVillains);
// Set { 'mikasa', 'armin' }

Union

The .union() method returns a new set containing the elements that are in either set.

const heroes = new Set(["eren", "mikasa", "armin", "reiner"]);
const villains = new Set(["eren", "reiner", "bertholdt", "annie"]);
const everyone = heroes.union(villains);
console.log(everyone);
// Set { 'eren', 'mikasa', 'armin', 'reiner', 'bertholdt', 'annie' }

There are some more set methods, but those are the big three.