can i listen to a function call using javascript?

Question

How can i listen to a specific function call with parametters using javascript:

example : when showname(2) is called i can do something like call another function to

Answer 1

One way to do it is to add a callback to the function, for example define:

function showname(firstname, lastname, callback){
    alert(firstname + lastname);
    if(callback) callback();
}

function showage(){ 
   alert("who's age?");
}

And call:

showname("John", "Doe", showage);