Question

I would like to know what is hide under some specifics ways to execute some code.

I have 3 different ways to do in my mind, but i really don’t know which is better on what kind of situation and why.
I just choose the Case 2 method most of the time for a syntaxical preference, but i am more and more wondering what are the advantages and disadvantages of each method.

Case 1:

var response = Func();
//Handle response...

Case 2:

Func(response){
  //Handle response...
};

Case 3:

Func({
  case_x: function(opt){
    //Handle an example case...
  }
});

Thanks for the explanations i am very curious about that !

Answer 1

Assuming that Func is an existing function:

Case 1 is if your function returns a value and you want to store the result, such as in:

function times_ten(num){ return num*10; }
var ten = 10;
var hundred = times_ten(ten);

So now you can use the variable hundred from now on.

Case 2 is if you are not returning a value, or you don’t need to save it:

function write_times_ten(num){ num = num*10; document.write(num);  }
var ten = 10;
var hundred = write_times_ten(ten);

Case 3 is slightly more complex.

If you do var something={a:function(){}} – By creating an object like this, you have all of your functions in the same scope, so you don’t pollute the global namespace. This is kind of like creating a class in other languages. jQuery is the biggest example of this I can think of, because for all of what it does, it all is processed by the object jQuery (or calling a function such as jQuery.parseJSON(json_string)

If you’re passing in an object with a function like that, then you are asking Func() to do something with that function you passed in, like so:

function do_something_times_ten(options){
    options.num = options.num*10;
    options.do_something(num);
}
var ten = 10;
do_something_times_ten({num:ten, 
                        do_something:function(num){
                                                     num = num*10;
                                                     document.write(num);  
                                                  }
                        }
);

Which would now write out 1000, not 100.