map.js

/********************************************************************************
 * 
 * 🗺️🗺️🗺️ Map 🗺️🗺️🗺️
 * Performs better in scenarios involving frequent additions and 
 * removals of key-value pairs.
 * 
 ********************************************************************************/

// 1️⃣ Main methods

const map = new Map();
map.set('key', 'value');

console.log(map.get('key')); // value
console.log(map.has('key')); // true
console.log(map.size); // 1

// 2️⃣ Iterating. 
// Keys are ordered by insertion time

map.set('aKey', 'this value appears last');

for (let [key, value] of map) {
  console.log(`${key}: ${value}`);
}

// 3️⃣ It is possible using objects and functions as keys

const objectKey = {};
map.set(objectKey, 'This is a value with an object acting as key');
console.log(map.get(objectKey)); // This is a value with an object acting as key

function functionKey() {};
map.set(functionKey, 'This is a value with a function acting as key');
console.log(map.get(functionKey)); // This is a value with a function acting as key