in js/bootstrap.bundle.js [2081:2116]
function arrow(_ref) {
var _state$modifiersData$;
var state = _ref.state,
name = _ref.name,
options = _ref.options;
var arrowElement = state.elements.arrow;
var popperOffsets = state.modifiersData.popperOffsets;
var basePlacement = getBasePlacement(state.placement);
var axis = getMainAxisFromPlacement(basePlacement);
var isVertical = [left, right].indexOf(basePlacement) >= 0;
var len = isVertical ? 'height' : 'width';
if (!arrowElement || !popperOffsets) {
return;
}
var paddingObject = toPaddingObject(options.padding, state);
var arrowRect = getLayoutRect(arrowElement);
var minProp = axis === 'y' ? top : left;
var maxProp = axis === 'y' ? bottom : right;
var endDiff = state.rects.reference[len] + state.rects.reference[axis] - popperOffsets[axis] - state.rects.popper[len];
var startDiff = popperOffsets[axis] - state.rects.reference[axis];
var arrowOffsetParent = getOffsetParent(arrowElement);
var clientSize = arrowOffsetParent ? axis === 'y' ? arrowOffsetParent.clientHeight || 0 : arrowOffsetParent.clientWidth || 0 : 0;
var centerToReference = endDiff / 2 - startDiff / 2; // Make sure the arrow doesn't overflow the popper if the center point is
// outside of the popper bounds
var min = paddingObject[minProp];
var max = clientSize - arrowRect[len] - paddingObject[maxProp];
var center = clientSize / 2 - arrowRect[len] / 2 + centerToReference;
var offset = within(min, center, max); // Prevents breaking syntax highlighting...
var axisProp = axis;
state.modifiersData[name] = (_state$modifiersData$ = {}, _state$modifiersData$[axisProp] = offset, _state$modifiersData$.centerOffset = offset - center, _state$modifiersData$);
}