function flip()

in static/js/popper.js [1507:1588]
57 lines of code
41 McCabe index (conditional complexity)

  function flip(data, options) {
    // if `inner` modifier is enabled, we can't use the `flip` modifier
    if (isModifierEnabled(data.instance.modifiers, 'inner')) {
      return data;
    }

    if (data.flipped && data.placement === data.originalPlacement) {
      // seems like flip is trying to loop, probably there's not enough space on any of the flippable sides
      return data;
    }

    var boundaries = getBoundaries(data.instance.popper, data.instance.reference, options.padding, options.boundariesElement, data.positionFixed);

    var placement = data.placement.split('-')[0];
    var placementOpposite = getOppositePlacement(placement);
    var variation = data.placement.split('-')[1] || '';

    var flipOrder = [];

    switch (options.behavior) {
      case BEHAVIORS.FLIP:
        flipOrder = [placement, placementOpposite];
        break;
      case BEHAVIORS.CLOCKWISE:
        flipOrder = clockwise(placement);
        break;
      case BEHAVIORS.COUNTERCLOCKWISE:
        flipOrder = clockwise(placement, true);
        break;
      default:
        flipOrder = options.behavior;
    }

    flipOrder.forEach(function (step, index) {
      if (placement !== step || flipOrder.length === index + 1) {
        return data;
      }

      placement = data.placement.split('-')[0];
      placementOpposite = getOppositePlacement(placement);

      var popperOffsets = data.offsets.popper;
      var refOffsets = data.offsets.reference;

      // using floor because the reference offsets may contain decimals we are not going to consider here
      var floor = Math.floor;
      var overlapsRef = placement === 'left' && floor(popperOffsets.right) > floor(refOffsets.left) || placement === 'right' && floor(popperOffsets.left) < floor(refOffsets.right) || placement === 'top' && floor(popperOffsets.bottom) > floor(refOffsets.top) || placement === 'bottom' && floor(popperOffsets.top) < floor(refOffsets.bottom);

      var overflowsLeft = floor(popperOffsets.left) < floor(boundaries.left);
      var overflowsRight = floor(popperOffsets.right) > floor(boundaries.right);
      var overflowsTop = floor(popperOffsets.top) < floor(boundaries.top);
      var overflowsBottom = floor(popperOffsets.bottom) > floor(boundaries.bottom);

      var overflowsBoundaries = placement === 'left' && overflowsLeft || placement === 'right' && overflowsRight || placement === 'top' && overflowsTop || placement === 'bottom' && overflowsBottom;

      // flip the variation if required
      var isVertical = ['top', 'bottom'].indexOf(placement) !== -1;
      var flippedVariation = !!options.flipVariations && (isVertical && variation === 'start' && overflowsLeft || isVertical && variation === 'end' && overflowsRight || !isVertical && variation === 'start' && overflowsTop || !isVertical && variation === 'end' && overflowsBottom);

      if (overlapsRef || overflowsBoundaries || flippedVariation) {
        // this boolean to detect any flip loop
        data.flipped = true;

        if (overlapsRef || overflowsBoundaries) {
          placement = flipOrder[index + 1];
        }

        if (flippedVariation) {
          variation = getOppositeVariation(variation);
        }

        data.placement = placement + (variation ? '-' + variation : '');

        // this object contains `position`, we want to preserve it along with
        // any additional property we may add in the future
        data.offsets.popper = _extends({}, data.offsets.popper, getPopperOffsets(data.instance.popper, data.offsets.reference, data.placement));

        data = runModifiers(data.instance.modifiers, data, 'flip');
      }
    });
    return data;
  }