callback function javascript

Question

I'm working with MooTools and I have a problem with a callback function. This is a little exemple:

function func1(callback){
    var event = 'something';
    callback(event);
}

function func2(data){

}

var Obj = new Class({
    initialize: function(){
        this.data = "data";
        //there I want to use func1 and use func2 as callback and this.data as argument of func2
    }
});

So I try

func1(function(){
    func2(this.data);
});

But I can't use this.data in an anonymous function because this is not the same context.

And

func1(func2)

This didn't works because I can't pass this.data as argument.

This is juste a simple exemple, func1 comes from a library so I can't edit it.

Answer 1

So the library you are using allows you to supply a callback function, but it only takes one parameter.

function mycallback(data){
  //now i see my data
}

Let's call this library function libfunc, and you're calling it like this:

libfunc(param1, param2, mycallback);

The lib function returns its own data to your callback function. So far so good.

Now you need TWO parameters, let's call them data, and extra. You tried:

function mycallback(data, extra){

}

but the callback function will only pass info onto the first parameter, right?

do this:

libfunc(param1, param2, mycallback('hello'));

now your mycallback should return a function in itself:

function mycallback(extra){
    return function(data){
      //now both extra and data are visible
    }
}

mycallback('hello') returns a function that takes one parameter, which is compatible with your library callback function; yet it binds the 'hello' extra value to the function itself.

Answer 2

How about:

function func1(callback, data){
    var event = 'something';
    callback(event, data);
}

function func2(data, data){

}

var Obj = new Class({
    initialize: function(){
        this.data = "data";
        //there I want to use func1 and use func2 as callback and this.data as argument     of func2
    }
});

And then:

func1(func2, this.data);