code: function getResizeDirections(oldBounds, newBounds) {
    var directions = '';
  
    oldBounds = asTRBL(oldBounds);
    newBounds = asTRBL(newBounds);
  
    if (oldBounds.top > newBounds.top) {
      directions = directions.concat('n');
    }
  
    if (oldBounds.right < newBounds.right) {
      directions = directions.concat('w');
    }
  
    if (oldBounds.bottom < newBounds.bottom) {
      directions = directions.concat('s');
    }
  
    if (oldBounds.left > newBounds.left) {
      directions = directions.concat('e');
    }
  
    return directions;
  }
docs: Get directions of resize as {n|w|s|e} e.g. "nw".
  
  @param {Bounds} oldBounds
  @param {Bounds} newBounds
  
  @returns {string} Resize directions as {n|w|s|e}.