jquery arrays intersect

Question

I previously posted this question as jquery/javascript: arrays - jquery/javascript: arrays. But since I am a complete beginner I have formulated the question wrong and didn't understand the answers either.... :(

After failing to implement the given solutions I did some more looking around I found out that I need to compare 6 arrays of possible choices and intersect them to finally display only the overlapping values.

So this is, hopely, a clearer formulation:

I have 6 questions/6 groups of radio buttons for answers. Each answer has multiple values (they can range from 1 to 38 items to be displayed in final 'advice'). I am collecting the values of checked radios in arrays. I get 6 arrays.

How do I intersect 6 arrays in order to get one final array containing only intersecting values form all 6 choices? How do I turn items of this final array into selectors?

Can someone please help me? Thank you!

My script looks now like:

(function($){
  $.fn.checkboxval = function(){
      var outArr = [];
      this.filter(':checked').each(function(){
            outArr.push(this.getAttribute("value"));
      });
      return outArr;
  };
})
(jQuery);
$(function(){
  $('#link').click(function(){
    var valArr1 = $('#vraag1 input:radio:checked').checkboxval();
    var valArr2 = $('#vraag2 input:radio:checked').checkboxval();
    var valArr3 = $('#vraag3 input:radio:checked').checkboxval();
    var valArr4 = $('#vraag4 input:radio:checked').checkboxval();
    var valArr5 = $('#vraag5 input:radio:checked').checkboxval();
    var valArr6 = $('#vraag6 input:radio:checked').checkboxval();
// var newArray = $.merge(valArr1, valArr2, valArr3, valArr4, valArr5, valArr6); <- test to see if I can merge them
// $('#output').text(newArray.join(',')); <- test to see if I can join them
//$("#output").html($("#output").html().replace(/,/gi, ',#diet')); <- test to see if I can append text so it looks like the selectors of divs I need to display later
//    return false;
  });
});

my form/inputs looks like:

<input name="vraag1" type="radio" value="1a,4,5,12,13,17a,18,19,22,23,24,26,27,28,29,30,33,38,6" class="radio advice" id="vraag1-0" /><label for="vraag1-0">ja</label>
<br />
<input name="vraag1" type="radio" value="1b,1,2,3,7,8,11,9,14,15,16,17,20,21,25,31,34,35,36,37,10,32" class="radio advice" id="vraag1-1" /><label for="vraag1-1">nee</label>
<br />
<input name="vraag1" type="radio" value="1c,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,17a,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38" class="radio advice" id="vraag1-2" /><label for="vraag1-2">maakt mij niet uit</label>

Answer 1

With jQuery loaded, you can punch in the console:

a1=[1,2,3]
a2=[2,3,4,5]
$.map(a1,function(a){return $.inArray(a, a2) < 0 ? null : a;})

The output should be:

[2, 3]