function getContainingBlock()

in _/js/bootstrap.bundle.js [1991:2023]

• 23 lines of code
• 16 McCabe index (conditional complexity)

  function getContainingBlock(element) {
    var isFirefox = /firefox/i.test(getUAString());
    var isIE = /Trident/i.test(getUAString());

    if (isIE && isHTMLElement(element)) {
      // In IE 9, 10 and 11 fixed elements containing block is always established by the viewport
      var elementCss = getComputedStyle$1(element);

      if (elementCss.position === 'fixed') {
        return null;
      }
    }

    var currentNode = getParentNode(element);

    if (isShadowRoot(currentNode)) {
      currentNode = currentNode.host;
    }

    while (isHTMLElement(currentNode) && ['html', 'body'].indexOf(getNodeName(currentNode)) < 0) {
      var css = getComputedStyle$1(currentNode); // This is non-exhaustive but covers the most common CSS properties that
      // create a containing block.
      // https://developer.mozilla.org/en-US/docs/Web/CSS/Containing_block#identifying_the_containing_block

      if (css.transform !== 'none' || css.perspective !== 'none' || css.contain === 'paint' || ['transform', 'perspective'].indexOf(css.willChange) !== -1 || isFirefox && css.willChange === 'filter' || isFirefox && css.filter && css.filter !== 'none') {
        return currentNode;
      } else {
        currentNode = currentNode.parentNode;
      }
    }

    return null;
  } // Gets the closest ancestor positioned element. Handles some edge cases,