JavaScript Maps

JavaScript Maps are data structures that store key-value pairs, where each key is unique and maps to a corresponding value.

Maps in JavaScript were introduced in ECMAScript 6, and they provide a more flexible alternative to objects for mapping keys to values.

Essential Map Methods

Method	Description
new Map()	Creates a new Map
set()	Sets the value for a key in a Map
get()	Gets the value for a key in a Map
delete()	Removes a Map element specified by the key
has()	Returns true if a key exists in a Map
forEach()	Calls a function for each key/value pair in a Map
entries()	Returns an iterator with the [key, value] pairs in a Map
Property	Description
size	Returns the number of elements in a Map

How to Create a Map

For create a new Map, you can use the new keyword and the Map() constructor:

let myMap = new Map();

• You can add key-value pairs to the map using the set() method:

myMap.set("key1", "value1");
myMap.set("key2", "value2");

• You can also chain the set() method to add multiple key-value pairs in a single line of code:

myMap.set("key1", "value1").set("key2", "value2");

• To retrieve a value from the map, you can use the get() method and pass in the key:

console.log(myMap.get("key1")); // Output: "value1"

• You can also check if a key exists in the map using the has() method:

console.log(myMap.has("key1")); // Output: true

• To remove a key-value pair from the map, you can use the delete() method and pass in the key:

myMap.delete("key1");
console.log(myMap.has("key1")); // Output: false

• You can also clear all key-value pairs from the map using the clear() method:

myMap.clear();
console.log(myMap.size); // Output: 0

• Maps also have a size property that returns the number of key-value pairs in the map:

console.log(myMap.size); // Output: 1

Overall, Maps in JavaScript are a powerful tool for working with key-value data and provide a more flexible alternative to objects.