var graph = {
        _ds2: [],
        display_graph: function(){
            graph._data = [];
            _data = "class=graph&func=get_all";
            $.post(window.location.href, {async: false}, _data, function(data){
                var data = $.parseJSON(data);
                //console.log(data)
                for (var i = data.length - 1; i >= 0; i--) {
                    _ds1 = [];
                    _ds1.push(parseInt(data[i]['year']), parseInt(data[i]['income']));
                    graph._data.push(_ds1);
                };
               ///graph.create_graph(graph._ds2.reverse());
               //return graph._data;
            });
            return graph._data;
        }

$(document).ready(function(){
        /* graph 1*/
        console.log(graph.display_graph());
    });

function foo(){

    fooAjax(function(data){ console.log(data) } //data is the data retrieved by the ajax
}

fooAjax(callback){

    $.ajax({
           success: function(response) {
               callback(response)
           });
}