gistfile1.js

//create a var for tracking if the element
//is currently moving or not
var moving = false;

$('a').on('click', function(){
  var moveMe = $('#moveMe');
  
  //if the element is moving clear the queue
  //and stop the animation
  if( moving ){
      moveMe.clearQueue();
      moveMe.stop();
      //reset the moving variable
      moving = false;
    
    $(this).text('Start Animating');
      return;
  }
  
  $(this).text('Stop Animating');
  
  //set the moving variable to true
  moving = true;
  
  //queue the animations
  moveMe.slideUp(1500,updateQueueCount)
    .slideDown(1500,updateQueueCount)
    .slideUp(1500,updateQueueCount)
    .slideDown(1500,function(){
      //in the last animation's callback
      //reset moving to false
      moving = false;
      updateQueueCount();
    });
  
  updateQueueCount();
});

function updateQueueCount(){
  $('#count').text( 
    $('#moveMe').queue('fx').length 
  );
}