BoundingBox and LockY

Movement can be locked to X or Y axis and also you can provide element in options.boundingBox to limit crossing element borders.

Items are locked in Y axis movement and cannot cross its closest parent div.boundingBox, just try it your selves.

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  dragularService([$element.children()[0].children(), {
    boundingBox: $element.children()[0],
    lockY: true
  });