Map is an object in a javascript and it holds the key-value pairs in it. We can declare a map object by just writing --->

const map1 = new Map();

The key is always to be unique on a map. Or we can say it is unique in a map collection.

the first letter of the Map is always in capital letters. Let us illustrate with the help of the source code given below.

const map1  = new Map();
// set is used for pushing the key-value in a map.
map1.set('a',1);
map1.set('b',2);
map1.set('c',3);
map1.set('d',4);
// We will get the values of the key with the help of get(key); .
console.log(map1.get('b')); // 2

//Used for finding the size of the map object 
console.log(map1.size); // 4

// let us remove one key-value pair from a map 
map1.delete('a');

console.log(map1.size);  // 3