Passing a function as a parameter in JavaScript

Passing a function as an argument to the function is quite similar to the passing variable as an argument to the function. Below examples describes to passing a function as a parameter to another function.

Example 1: This example passes a function geeks_inner to the function geeks_outer as an argument.

filter_none

edit
close

play_arrow

link
brightness_4
code

<!DOCTYPE html> 
<html
    <head
        <title
            JavaScript | Pass a function as parameter 
        </title
    </head
      
    <body style = "text-align:center;"
          
        <h1 style = "color:green;"
            GeeksForGeeks 
        </h1
          
        <p
            Passing function as arguments. 
        </p
          
        <!-- Function call after clicking the button -->
        <button onclick = "geeks_outer(geeks_inner)"
            Click Here 
        </button>     
          
        <script
            function geeks_inner(value){
                return 'hello User!';
            }
            function geeks_outer(func){
                alert(func());
            }
        </script
    </body
</html>                    

chevron_right


Output:



  • Before clicking on the button:
  • After clicking on the button:

Example 2: This example passes a function geeks_inner alongwith a argument ‘Geeks!’ to the function geeks_outer as a argument.

filter_none

edit
close

play_arrow

link
brightness_4
code

<!DOCTYPE html> 
<html
    <head
        <title
            JavaScript | Pass a function as parameter 
        </title
    </head>     
      
    <body style = "text-align:center;"
          
        <h1 style = "color:green;"
            GeeksForGeeks 
        </h1
      
        <p
            Passing function as arguments. 
        </p>             
          
        <button onclick = "geeks_outer('Geeks!', geeks_inner)"
            Click Here 
        </button>         
          
        <!-- Script to uses function call using
            function as argument -->
        <script
            function geeks_inner(value){
                return 'hello '+value;
            }
            function geeks_outer(a, func){
                alert(func(a));
        }         
        </script
    </body
</html>                    

chevron_right


Output:

  • Before clicking on the button:
  • After clicking on the button:


My Personal Notes arrow_drop_up

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.