in content/js/bootstrap.bundle.js [2016:2066]
function getBoundaries(popper, reference, padding, boundariesElement) {
var fixedPosition = arguments.length > 4 && arguments[4] !== undefined ? arguments[4] : false;
// NOTE: 1 DOM access here
var boundaries = { top: 0, left: 0 };
var offsetParent = fixedPosition ? getFixedPositionOffsetParent(popper) : findCommonOffsetParent(popper, reference);
// Handle viewport case
if (boundariesElement === 'viewport') {
boundaries = getViewportOffsetRectRelativeToArtbitraryNode(offsetParent, fixedPosition);
} else {
// Handle other cases based on DOM element used as boundaries
var boundariesNode = void 0;
if (boundariesElement === 'scrollParent') {
boundariesNode = getScrollParent(getParentNode(reference));
if (boundariesNode.nodeName === 'BODY') {
boundariesNode = popper.ownerDocument.documentElement;
}
} else if (boundariesElement === 'window') {
boundariesNode = popper.ownerDocument.documentElement;
} else {
boundariesNode = boundariesElement;
}
var offsets = getOffsetRectRelativeToArbitraryNode(boundariesNode, offsetParent, fixedPosition);
// In case of HTML, we need a different computation
if (boundariesNode.nodeName === 'HTML' && !isFixed(offsetParent)) {
var _getWindowSizes = getWindowSizes(),
height = _getWindowSizes.height,
width = _getWindowSizes.width;
boundaries.top += offsets.top - offsets.marginTop;
boundaries.bottom = height + offsets.top;
boundaries.left += offsets.left - offsets.marginLeft;
boundaries.right = width + offsets.left;
} else {
// for all the other DOM elements, this one is good
boundaries = offsets;
}
}
// Add paddings
boundaries.left += padding;
boundaries.top += padding;
boundaries.right -= padding;
boundaries.bottom -= padding;
return boundaries;
}