Map

Map keeps track of key/value pairs in insertion order

let yum = new Map();
// Set key-value pairs
yum.set('apple': 8);
yum.set('banana': 10);
yum.set('chicken': 0);
// Get value
yum.get('apple'); // 8
// Check if value exists
yum.has('apple'); // true
// Delete key-value pair
yum.delete('chicken');
// Check size
yum.size; // 2

for(let [key, value] of yum) {
    console.log(key + value);
}
// Delete EVERYTHING
yum.clear();

Set

Collects of values. Keeps track of insertion order. Elements may only occur once.

let mySet = new Set();
// Insert elements
mySet.add(1);
mySet.add('bob');
mySet.add('apple');
// Check if set as an element
mySet.has(1); // true
// Remove element
mySet.delete('bob');
// Size
mySet.size; // 2

for(let v of mySet) {
    console.log(v); // 1, 'apple'
}