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.
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<!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> |
Output:
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Before clicking on the button:
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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.
<!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> |
Output:
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Before clicking on the button:
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After clicking on the button:
