lab_work3

node_modules/@popperjs/core/lib/dom-utils/getOffsetParent.js.flow

@@ -0,0 +1,93 @@
+// @flow
+import getWindow from './getWindow';
+import getNodeName from './getNodeName';
+import getComputedStyle from './getComputedStyle';
+import { isHTMLElement, isShadowRoot } from './instanceOf';
+import isTableElement from './isTableElement';
+import getParentNode from './getParentNode';
+import getUAString from '../utils/userAgent';
+
+function getTrueOffsetParent(element: Element): ?Element {
+  if (
+    !isHTMLElement(element) ||
+    // https://github.com/popperjs/popper-core/issues/837
+    getComputedStyle(element).position === 'fixed'
+  ) {
+    return null;
+  }
+
+  return element.offsetParent;
+}
+
+// `.offsetParent` reports `null` for fixed elements, while absolute elements
+// return the containing block
+function getContainingBlock(element: Element) {
+  const isFirefox = /firefox/i.test(getUAString());
+  const 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
+    const elementCss = getComputedStyle(element);
+    if (elementCss.position === 'fixed') {
+      return null;
+    }
+  }
+
+  let currentNode = getParentNode(element);
+
+  if (isShadowRoot(currentNode)) {
+    currentNode = currentNode.host;
+  }
+
+  while (
+    isHTMLElement(currentNode) &&
+    ['html', 'body'].indexOf(getNodeName(currentNode)) < 0
+  ) {
+    const css = getComputedStyle(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,
+// such as table ancestors and cross browser bugs.
+export default function getOffsetParent(element: Element) {
+  const window = getWindow(element);
+
+  let offsetParent = getTrueOffsetParent(element);
+
+  while (
+    offsetParent &&
+    isTableElement(offsetParent) &&
+    getComputedStyle(offsetParent).position === 'static'
+  ) {
+    offsetParent = getTrueOffsetParent(offsetParent);
+  }
+
+  if (
+    offsetParent &&
+    (getNodeName(offsetParent) === 'html' ||
+      (getNodeName(offsetParent) === 'body' &&
+        getComputedStyle(offsetParent).position === 'static'))
+  ) {
+    return window;
+  }
+
+  return offsetParent || getContainingBlock(element) || window;
+}