multiple ajax success callback defer

multiple ajax success callback defer

In my javascript, I have the following scenario:
call_A(success_A)

call_B(success_B)

fucntion call_A(success){
   // make ajax request
   success(result)
}

function call_B(success){
    //make ajax
    request success(result)
}

function success_A(){
//set data to be used by success_B
}

function success_B(){
 ..do some stuff
}

I want to make both call_A and call_B one after the other so that ajax calls are made (to save time).
I do not have the option for changing call_A and call_B function headers, so the call to these function has to be made specifying the success callback function.
What I want is that regardless of which of the 2 ajax call finishes first, I want success_A get called before success_B, because B depends on A's data. What is the best way of getting this done?