function getOffsetRectRelativeToArbitraryNode()

in static/js/popper.js [487:537]
37 lines of code
11 McCabe index (conditional complexity)

  function getOffsetRectRelativeToArbitraryNode(children, parent) {
    var fixedPosition = arguments.length > 2 && arguments[2] !== undefined ? arguments[2] : false;

    var isIE10 = isIE(10);
    var isHTML = parent.nodeName === 'HTML';
    var childrenRect = getBoundingClientRect(children);
    var parentRect = getBoundingClientRect(parent);
    var scrollParent = getScrollParent(children);

    var styles = getStyleComputedProperty(parent);
    var borderTopWidth = parseFloat(styles.borderTopWidth, 10);
    var borderLeftWidth = parseFloat(styles.borderLeftWidth, 10);

    // In cases where the parent is fixed, we must ignore negative scroll in offset calc
    if (fixedPosition && isHTML) {
      parentRect.top = Math.max(parentRect.top, 0);
      parentRect.left = Math.max(parentRect.left, 0);
    }
    var offsets = getClientRect({
      top: childrenRect.top - parentRect.top - borderTopWidth,
      left: childrenRect.left - parentRect.left - borderLeftWidth,
      width: childrenRect.width,
      height: childrenRect.height
    });
    offsets.marginTop = 0;
    offsets.marginLeft = 0;

    // Subtract margins of documentElement in case it's being used as parent
    // we do this only on HTML because it's the only element that behaves
    // differently when margins are applied to it. The margins are included in
    // the box of the documentElement, in the other cases not.
    if (!isIE10 && isHTML) {
      var marginTop = parseFloat(styles.marginTop, 10);
      var marginLeft = parseFloat(styles.marginLeft, 10);

      offsets.top -= borderTopWidth - marginTop;
      offsets.bottom -= borderTopWidth - marginTop;
      offsets.left -= borderLeftWidth - marginLeft;
      offsets.right -= borderLeftWidth - marginLeft;

      // Attach marginTop and marginLeft because in some circumstances we may need them
      offsets.marginTop = marginTop;
      offsets.marginLeft = marginLeft;
    }

    if (isIE10 && !fixedPosition ? parent.contains(scrollParent) : parent === scrollParent && scrollParent.nodeName !== 'BODY') {
      offsets = includeScroll(offsets, parent);
    }

    return offsets;
  }