Function isElement

javascript/atoms/typescript/get-attribute.ts:81–94

(node: unknown, tagName?: string)

  }

  function isElement(node: unknown, tagName?: string): node is Element {
    const elem = node as { nodeType?: number; tagName?: string } | null;
    if (!elem || elem.nodeType !== 1) {
      return false;
    }
    if (!tagName) {
      return true;
    }
    const normalizedTag = tagName.toUpperCase();
    if (node instanceof HTMLFormElement) {
      return normalizedTag === 'FORM';
    }
    return typeof elem.tagName === 'string' && elem.tagName.toUpperCase() === normalizedTag;
  }

  function isSelectable(element: Element): boolean {
    if (isElement(element, 'OPTION')) {