Set

The Set object is similar to Map() but lets you store unique values in a list rather than key/values.

const drinks = new Set();
drinks.add('coke');
drinks.add('pepsi');

//or

const drinks = new Set(['coke', 'pepsi']);

We can find the size and interrogate the Set.

drinks.size; // 3
drinks.has('orange'); //false
drinks.has('coke'); //true

We can also iterate over the set with a for-of loop or froEach().

for(let drink of drinks) {
    console.log(drink);
}

drinks.forEach((drink) => {
    console.log(drink);
})

we can convert the set to an array simply using spread operator:

let drinksArray = [...drinks];

Finally, we can clear the map of one or all values

drinks.delete('coke');
drinks.clear();

Uniqueness

So far, this essentially looks like a fancy Array. An important distinction is that a Set only stores unique values...

const drinks = new Set(['coke', 'pepsi', 'coke', 'pepsi', 'tango']);
console.log([...drinks]); // ["coke", "pepsi", "tango"]

WeakSet() A WeakSet() is the same as a Map() but the values can be garbage collected for better memory management.

You can’t iterate over the contents – neither the keys, nor the values, nor the entries. You can’t clear a WeakSet, either.