title: Use jQuery to set a variable for a JavaScript function
body: <p>I have a little problem mixing a JavaScript library (Polymaps) and jQuery.
  I'd like to call a different file everytime the user selects a value from the datepicker. </p>
  
  <p>The filename syntax is: </p>
  
  <pre><code>4sq_'the selected day value' _ 'the selected month value'.json
  </code></pre>
  
  <p>This is the datepicker code:</p>
  
  <pre><code>$("#datepicker").datepicker({
      dateFormat: 'yy/mm/dd',
      inline: true,
      minDate: new Date(2011, 8 - 1, 20),
      maxDate:new Date(2011, 12 - 1, 31),
      altField: '#datepicker_value',
        onSelect: function(){
          var selDay = $("#datepicker").datepicker('getDate').getDate();                 
          var selMonth = $("#datepicker").datepicker('getDate').getMonth() + 1;             
          var selYear = $("#datepicker").datepicker('getDate').getFullYear();
  
          plotMap()
      }
  });
  </code></pre>
  
  <p>and the name of the file contains the values of the selection like below:</p>
  
  <pre><code>function plotMap(){
      map.add(po.geoJson()
         .url("4sq_"+selDay+"_"+selMonth+".json")
         .on("load", loadAreas));
  };
  </code></pre>
  
  <p>I also tried the code:</p>
  
  <pre><code>function plotMap(){
      map.add(po.geoJson()
         .url("4sq_"+
                     $("#datepicker").datepicker('getDate').getDate()
              +"_"+
                    $("#datepicker").datepicker('getDate').getMonth()
              +".json")
         .on("load", loadAreas));
  };
  </code></pre>
  
  <p>but it throws me an <code>Access to restricted URI denied</code> error.</p>
  
  <p>What I'm doing wrong? Any suggestion?</p>