How to get variable value outside a function IN jquery

I have a variable i assign value to it inside a function now i want to get this value outside of this variable but i get undefined, below is my code. I have select2 on my page whcih i want to populate with some data depend on what users choices are, i allow a user to choose a radio button and i get the value of the radio button to determine which data to display in the select menu. Now after my coding i could alert var size_data within the onclick event function but couldn't get this value to the select2 where i need it, any help on this will be appreciated

Note var size_data is a global variable and the variable that holds different sizes are also global variable

see my DEMO ON FIDDLE

var uk_size = [{ id: '8', text: '8' },
                { id: '10', text: '10' }, 
                { id: '12', text: '12' },
            ];
var us_size = [{ id: '4', text: '4' },
                { id: '6', text: '6' }, 
                { id: '8', text: '8' },
                { id: '10', text: '10' }, 
            ];
var eu_size = [{ id: '34', text: '34' },
                { id: '36', text: '36' }, 
                { id: '38', text: '38' },
            ];
var ng_size = [{ id: 'XS', text: 'XS' },
                { id: 'S', text: 'S' }, 
                { id: 'M', text: 'M' },
            ];
var size_data = ng_size; //default value;
//alert(ng_size);
   $("#size-style input:radio").on('click',function() {
              //alert(ng_size);

                  var size_style ="";
                size_style = $(this).val();
                if (size_style === "ng-size"){
                      size_data = ng_size;  
                }else if(size_style === "uk-size"){
                      size_data = uk_size; 
                }else if(size_style === "us-size"){
                      size_data = us_size;
                }else{
                    size_data = eu_size;
                }
                alert(size_data);//can alert jquery object here
    });



$('select.size-select').select2({
        name: 'size',
        value: 'S',
        data: size_data,
        tags: "true",
        placeholder: "Select size",
        allowClear: true
    });