title: While mousedown JS
body: <p>I'm trying to run a function while <code>mousedown</code> but for the life of me I can't get it to work while holding down but everything works by just clicking. I'm trying to change color of countries on a map as I hold down. 
  Here's my code: </p>
  
  <pre><code>    var int;
      var mouseStillDown = false;
  
        function mousedown(geography) 
        {     console.log('mousedown '+mousedownID);
               mouseStillDown = true;
            int = setInterval( performWhileMouseDown(geography), 100);
        }
  
  
  
      function mouseup() 
      {
          clearInterval(int);  
          mouseStillDown = false;
      }
  
       function mouseout() 
      {
          clearInterval(int);  
      }
  
        function performWhileMouseDown(geography)
         {
               if (!mouseStillDown)
                {console.log('error');}
  
              if (mouseStillDown) {
             if(data[geography.id])
              {
                data[geography.id] ++;
              }else
                {
                  data[geography.id] = 1;
                }
              var m = {};                                        
              m[geography.id] = color(data[geography.id]);
              map.updateChoropleth(m);
                }
  
              /* if (mouseStillDown)
                { setInterval(performWhileMouseDown(geography), 100); }*/
        }
  </code></pre>