JavaScript | weakMap.has() with Examples

The weakMap.has() is an inbuilt function in JavaScript which is used to return a boolean value which indicates whether an element with a particular key presents in the weakmap object or not.
Syntax:

weakMap.has(key);

Parameters: It accepts a parameter ‘key’ which is the key of the element which is going to be tested for presence in the object weakmap.
Return values: It returns true if the element with the specified key is present in the weakmap object otherwise it returns false.

JavaScripts to show the working of this function:

Code #1:

filter_none

edit
close

play_arrow

link
brightness_4
code

<script>
  
   // Creating a WeakMap() object
   const weakmap1 = new WeakMap();
     
   // Creating a key "key1"
   const key1 = {};
     
   // setting element 'gfg' to the key "key1"
   weakmap1.set(key1, 'gfg');
     
   // Testing whether the key is present 
   // in the weakMap() object or not
   document.write(weakmap1.has(key1));
  
</script>

chevron_right






                        filter_none








Output:




true


Code #2:











                                    filter_none




                                    edit

                                    close




                                    play_arrow




                                    link

                                    brightness_4

                                    code
                                




















<script> 


  


   // Creating a WeakMap() object 


   const weakmap1 = new WeakMap(); 


     


   // Creating a key "key1" 


   const key1 = {}; 


     


   // Testing whether the key is present  


   // in the weakMap() object or not 


   document.write(weakmap1.has(key1)); 


  


</script> 



















                        chevron_right







                        filter_none








Output:


false


Here output is false because the key “key1” has not been set at the end of the weakMap object.





    

        My Personal Notes
        arrow_drop_up
    

    

        
        

            
            
        

    


Recommended Posts:
ShivamKD
Check out this Author's contributed articles.
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.