Determining arguments in callback functions

[danielleng]

Hey guys, right now I'm trying to get response from the server via a callback function, like this:

QueryDatabase.validateLogin(email, password, function(response, e){
                                            console.log(response);
                                            });

QueryDatabase represents my PHP file, and the validateLogin is a function that takes email and password as arguments. (the 3rd argument, function() is actually the callback argument)

My question is, how do you determine what kind of arguments go into the callback function() ? In the extjs API there is an example that goes like this:

store.load ({
scope   : this,
callback: function(records, operation, success) {
       //the operation object contains all of the details of the load operation 
       console.log(records);
} });

As you can see the arguments are now (records, operation, success)... but how do u know u have to use those?

[mitchellsimoens]

If you don't know what arguments there are in a function, look at arguments:

console.log(arguments);

That keyword doesn't care if it is listed as an argument in the function.

[danielleng]

Thanks, understood it now.