Does JavaScript Have Map Data Structure?


Scott Campbell

JavaScript is a versatile programming language that offers a wide range of data structures to handle complex tasks efficiently. One such data structure that JavaScript provides is the Map.

The Map data structure allows you to store and retrieve data in a key-value format. It is similar to the Object data structure, but with some key differences.

Creating a Map

To create a Map in JavaScript, you can use the Map() constructor. Here’s an example:

    let map = new Map();

This creates an empty Map. You can also initialize a Map with key-value pairs:

    let map = new Map([
      ['key1', 'value1'],
      ['key2', 'value2'],
      ['key3', 'value3']

Adding and Retrieving Data from a Map

To add data to a Map, you can use the set() method:

    map.set('key4', 'value4');

You can retrieve the value associated with a specific key using the get() method:

    let value = map.get('key1');
    console.log(value); // Output: value1

Iterating over a Map

You can iterate over the elements of a Map using various methods. One common approach is to use the for..of loop:

    for (let [key, value] of map) {
      console.log(key + ' = ' + value);

This will output all the key-value pairs in the Map.

Checking if a Key Exists

To check if a specific key exists in a Map, you can use the has() method:

    let hasKey = map.has('key1');
    console.log(hasKey); // Output: true

Deleting Data from a Map

To remove a specific key-value pair from a Map, you can use the delete() method:


This will remove the key-value pair with ‘key2’ from the Map.

The Map Size

You can get the number of elements in a Map using the size property:

    let size = map.size;
    console.log(size); // Output: 3


The Map data structure in JavaScript provides an efficient way to store and retrieve data using key-value pairs. It offers methods for adding, retrieving, iterating over, checking existence of keys, and deleting elements. By incorporating Maps into your JavaScript code, you can enhance its functionality and performance.

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