code: function(node) {
          // Re-adjust the offset to match the parent container
          // is() fails when checking against window
          if (container[0] !== window) {
              var conOffset = container.offset();
  
              left -= conOffset.left;
              top -= conOffset.top;
          }
      }
docs: Verify that the item is within the current browser viewport.
  
  @param {jQuery} node
  @returns {bool}