How to add an array of values to a Set

Question

The old school way of adding all values of an array into the Set is:

// for the sake of this example imagine this set was created somewhere else 
// and I ca         


        

Answer 1

You can also use Array.reduce():

const mySet = new Set();
mySet.add(42); // Just to illustrate that an existing Set is used

[1, 2, 3].reduce((s, e) => s.add(e), mySet);

Answer 2

This is IMO the most elegant

// for a new Set 
const x = new Set([1,2,3,4]);

// for an existing Set
const y = new Set();

[1,2,3,4].forEach(y.add, y);

Answer 3

How about using the spread operator to easily blend your new array items into an existing set?

const mySet = new Set([1,2,3,4])
const additionalSet = [5,6,7,8,9]
mySet = new Set([...mySet, ...additionalSet])

JSFIDDLE