feat: create helpers for working with the element as part esl-util DO…

…M helpers

src/modules/esl-utils/dom/element.ts

@@ -0,0 +1,41 @@
+import {getWindow} from './window';
+
+/**
+ * Get an object containing the values of all CSS properties of an element.
+ * @param element - element for which to get the computed style
+ * */
+export function getComputedStyle(element: Element): CSSStyleDeclaration {
+  return getWindow(element).getComputedStyle(element);
+}
+
+/**
+ * Get the Element that is the root element of the document.
+ * @param element - element for which to get the document element
+ * */
+export function getDocumentElement(element: Element | Window): Element {
+  return ((element instanceof Window
+    ? element.document
+    : element.ownerDocument) || window.document).documentElement;
+}
+
+/**
+ * Get the name of node.
+ * @param element - element for which to get the name
+ */
+export function getNodeName(element?: Node | Window): string {
+  return element && !(element instanceof Window)? (element.nodeName).toLowerCase() : '';
+}
+
+/**
+ * Get the parent of the specified element in the DOM tree.
+ * @param element - element for which to get the parent
+ */
+export function getParentNode(element: Element | ShadowRoot): Node {
+  if (getNodeName(element) === 'html') {
+    return element;
+  }
+
+  return (element instanceof ShadowRoot
+    ? element.host
+    : element.assignedSlot || element.parentNode) || getDocumentElement(element as Element);
+}