What is JavaScript Map and how to use it ?

What is Map?

A Map in JavaScript is a collection of key-value pairs where keys can be any data type. Unlike objects, keys in a Map maintain insertion order. It provides methods to set, get, delete, and iterate over elements efficiently, making it useful for data storage and retrieval tasks.

Syntax

new Map( );
new Map( [iterable_objects] );

Return type: It returns a new map object.

Parameters: An array or iterable object.

Example: Creating and Using a Map

In this example we creates a Map named company with key-value pairs. The print function logs each value followed by its corresponding key using company.forEach(print).

const company = new Map([
    ["name", "GFG"],
    ["no_of_employee", 200],
    ["category", "education"]
]);
function print(key, values) {
    console.log(values + "=>" + key);
}
company.forEach(print);

name=>GFG
no_of_employee=>200
category=>education

Example: Iterating Over a Map Using forEach()

In this example we creates a Map named company and populates it with key-value pairs. The print function logs each value followed by its corresponding key using company.forEach(print).

const company = new Map();
company.set("name", "GFG");
company.set("no_of_employee", 200);
company.set("category", "education");
function print(key, values) {
    console.log(values + "=>" + key);
}
company.forEach(print);

name=>GFG
no_of_employee=>200
category=>education

JavaScript Map Properties

A JavaScript property is a member of an object that associates a key with a value.

• Instance Properties: An instance property is a property that has a new copy for every new instance of the class.

JavaScript Map Methods

JavaScript methods are actions that can be performed on objects.

• Instance Methods: If the method is called on the instance of a Map then it is called an instance method of Map.