Map.clear( ) In JavaScript

What is a map in JavaScript?

  • Map is a data structure in JavaScript which allows storing of [key, value] pairs where any value can be either used as a key or value.
  • The keys and values in the map collection may be of any type and if a value is added to the map collection using a key which already exists in the collection, then the new value replaces the old value.
  • The iteration of elements in a map object is done in the insertion order and a “for…” loop returns an array of all [key, value] pairs for each iteration.

Differences between Objects and Maps in JavaScript
Both of these data structures are similar in many ways such as both store values using keys, allow retrieval of those values using keys, deletion of keys and verify whether a key holds any value or not. However, there are quite significant differences between Objects and Maps in JavaScript which make the usage of maps a better and more preferable option in many cases.

  • The keys used in maps can be any type of values such as functions, objects etc whereas the keys in objects are limited to symbols and strings.
  • The size of a map can be known easily by using the size property but while dealing with objects, the size has to be determined manually.
  • A Map should be preferred in cases where the requirement involves frequent addition and removal of [key, value] pairs because a map is an iterable data type and can be directly iterated whereas iterating an object requires obtaining its keys in a specific manner.

Map.clear() Method in JavaScript
The Map.clear() method in JavaScript is used for the removal of all the elements from a map and make it empty. It removes all the [key, value] from the map. No arguments are required to be sent as parameters to the Map.clear() method and it returns an undefined return value.

Syntax:

mapObj.clear()

Parameters Used:
No parameters are required in the Map.clear() method.

Return Value:
Map.clear() method has an undefined return type.

Examples of the above function are provided below.

Examples:

Input : var myMap = new Map();
        myMap.set(0, 'geeksforgeeks');
        console.log(myMap.size);
        myMap.clear();
        console.log(myMap.size);

Output: 1
        0

Explanation: In this example, a map object “myMap” has been created with a single [key, value] pair and the Map.clear() method is used to remove the [key, value] pair from “myMap”. myMap.size() is used to check the number of [key, value] pairs belonging to the map object.

Input : var myMap = new Map();
        myMap.set(0, 'geeksforgeeks');
        myMap.set(1, 'is an online portal');
        myMap.set(2, 'for geeks');
        console.log(myMap.size);
        myMap.clear();
        console.log(myMap.size);
Output : 3
         0

Explanation: In this example, a map object “myMap” has been created with a three [key, value] pairs and the Map.clear() method is used to remove all the [key, value] pairs from “myMap”. myMap.size() is used to check the number of [key, value] pairs belonging to the map object.

Codes for the above function are provided below.

Code 1:

filter_none

edit
close

play_arrow

link
brightness_4
code

<script>
  
    // creating a map object
    var myMap = new Map();
  
// Adding [key, value] pair to the map
myMap.set(0, 'geeksforgeeks');
  
// displaying the number of 
// [key, value] pairs the map has
document.write(myMap.size);
document.write("<br>");
  
// removing the [key, value] pairs of
// the map using Map.clear() method
myMap.clear();
  
// displaying the number of 
// [key, value] pairs the map has
document.write(myMap.size);
  
</script>                    s

chevron_right


OUTPUT :

1
0

Code 2:

filter_none

edit
close

play_arrow

link
brightness_4
code

<script>
    // creating a map object
    var myMap = new Map();
  
// Adding [key, value] pair to the map
myMap.set(0, 'geeksforgeeks');
myMap.set(1, 'is an online portal');
myMap.set(2, 'for geeks');
  
// displaying the number of 
// [key, value] pairs the map has
document.write(myMap.size);
document.write("<br>");
  
// removing the [key, value] pairs
// of the map using Map.clear() method
myMap.clear();
  
// displaying the number of
// [key, value] pairs the map has
document.write(myMap.size);
  
< /script>                    

chevron_right


OUTPUT :

3
0

Applications:

  • Map.clear() Method is used to remove all the [key, value] pairs of a map.
  • Let’s see a JavaScript Program :

    filter_none

    edit
    close

    play_arrow

    link
    brightness_4
    code

    <script>
      
        // creating a map object
        var myMap = new Map();
      
    // Adding [key, value] pair to the map
    myMap.set(0, 'Maps');
    myMap.set(1, 'in JavaScript');
      
    // displaying the number of
    // [key, value] pairs the map has
    document.write(myMap.size);
    document.write("<br>");
      
    // removing the [key, value] pairs of
    // the map using Map.clear() method
    myMap.clear();
      
    // displaying the number of 
    // [key, value] pairs the map has
    document.write(myMap.size);
      
    <script>                    

    chevron_right

    
    

    OUTPUT :

         2
         0
    

Exceptions :

  • If the variable is not of the Map type then the Map.entries() operation throws a TypeError.

Reference :https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/clear



My Personal Notes arrow_drop_up

I am a technology enthusiast who has a keen interest in programming I am pursuing Engineering in Computer Science from GEU, Dehradun I like to unwind by watching movies and English sitcomsI have a keen interest in music

If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.