DOM Core

/**
 * Main document interface for DOM tree management
 */
class Document extends Node {
  /** Document element (html element) */
  readonly documentElement: Element | null;
  
  /** Document head element */
  readonly head: HTMLHeadElement | null;
  
  /** Document body element */
  readonly body: HTMLBodyElement | null;
  
  /** Document title */
  title: string;
  
  /** Create new element with specified tag name */
  createElement(qualifiedName: string, options?: { is?: string }): HTMLElement;
  
  /** Create new text node */
  createTextNode(data: string): Text;
  
  /** Create new comment node */
  createComment(data: string): Comment;
  
  /** Create new document fragment */
  createDocumentFragment(): DocumentFragment;
  
  /** Create new attribute */
  createAttribute(name: string): Attr;
  
  /** Get element by ID */
  getElementById(id: string): Element | null;
  
  /** Get elements by tag name */
  getElementsByTagName(tagName: string): HTMLCollection;
  
  /** Get elements by class name */
  getElementsByClassName(className: string): HTMLCollection;
  
  /** Query selector (returns first match) */
  querySelector(selector: string): Element | null;
  
  /** Query selector all (returns all matches) */
  querySelectorAll(selector: string): NodeList;
  
  /** Import node from another document */
  importNode(node: Node, deep?: boolean): Node;
  
  /** Adopt node from another document */
  adoptNode(node: Node): Node;
}

/**
 * HTML-specific document implementation
 */
class HTMLDocument extends Document {
  /** Document cookie string */
  cookie: string;
  
  /** Document ready state */
  readonly readyState: DocumentReadyState;
  
  /** Document character set */
  readonly characterSet: string;
  
  /** Document URL */
  readonly URL: string;
  
  /** Document domain */
  domain: string;
  
  /** Document referrer */
  readonly referrer: string;
  
  /** Write content to document */
  write(content: string): void;
  
  /** Write line to document */
  writeln(content: string): void;
  
  /** Open document for writing */
  open(): void;
  
  /** Close document */
  close(): void;
}

/**
 * XML-specific document implementation
 */
class XMLDocument extends Document {
  /** XML version */
  readonly xmlVersion: string | null;
  
  /** XML encoding */
  readonly xmlEncoding: string | null;
  
  /** XML standalone flag */
  readonly xmlStandalone: boolean;
}

/**
 * Base class for all DOM nodes
 */
class Node extends EventTarget {
  /** Node type constant */
  readonly nodeType: number;
  
  /** Node name */
  readonly nodeName: string;
  
  /** Node value */
  nodeValue: string | null;
  
  /** Text content of node and descendants */
  textContent: string | null;
  
  /** Parent node */
  readonly parentNode: Node | null;
  
  /** Parent element */
  readonly parentElement: Element | null;
  
  /** Child nodes */
  readonly childNodes: NodeList;
  
  /** First child node */
  readonly firstChild: Node | null;
  
  /** Last child node */
  readonly lastChild: Node | null;
  
  /** Previous sibling node */
  readonly previousSibling: Node | null;
  
  /** Next sibling node */
  readonly nextSibling: Node | null;
  
  /** Owner document */
  readonly ownerDocument: Document | null;
  
  /** Check if node has child nodes */
  hasChildNodes(): boolean;
  
  /** Append child node */
  appendChild(node: Node): Node;
  
  /** Insert node before reference node */
  insertBefore(node: Node, referenceNode: Node | null): Node;
  
  /** Replace child node */
  replaceChild(newNode: Node, oldNode: Node): Node;
  
  /** Remove child node */
  removeChild(node: Node): Node;
  
  /** Clone node */
  cloneNode(deep?: boolean): Node;
  
  /** Check if node contains another node */
  contains(node: Node | null): boolean;
  
  /** Compare document position */
  compareDocumentPosition(node: Node): number;
  
  /** Normalize node */
  normalize(): void;
}

// Node type constants
const enum NodeType {
  ELEMENT_NODE = 1,
  ATTRIBUTE_NODE = 2,
  TEXT_NODE = 3,
  CDATA_SECTION_NODE = 4,
  PROCESSING_INSTRUCTION_NODE = 7,
  COMMENT_NODE = 8,
  DOCUMENT_NODE = 9,
  DOCUMENT_TYPE_NODE = 10,
  DOCUMENT_FRAGMENT_NODE = 11
}

/**
 * Generic DOM element class
 */
class Element extends Node {
  /** Element tag name */
  readonly tagName: string;
  
  /** Element ID */
  id: string;
  
  /** Element class name */
  className: string;
  
  /** Element class list */
  readonly classList: DOMTokenList;
  
  /** Element attributes */
  readonly attributes: NamedNodeMap;
  
  /** Inner HTML content */
  innerHTML: string;
  
  /** Outer HTML content */
  outerHTML: string;
  
  /** Element children */
  readonly children: HTMLCollection;
  
  /** First element child */
  readonly firstElementChild: Element | null;
  
  /** Last element child */
  readonly lastElementChild: Element | null;
  
  /** Previous element sibling */
  readonly previousElementSibling: Element | null;
  
  /** Next element sibling */
  readonly nextElementSibling: Element | null;
  
  /** Child element count */
  readonly childElementCount: number;
  
  /** Get attribute value */
  getAttribute(name: string): string | null;
  
  /** Set attribute value */
  setAttribute(name: string, value: string): void;
  
  /** Remove attribute */
  removeAttribute(name: string): void;
  
  /** Check if attribute exists */
  hasAttribute(name: string): boolean;
  
  /** Get attribute node */
  getAttributeNode(name: string): Attr | null;
  
  /** Set attribute node */
  setAttributeNode(attr: Attr): Attr | null;
  
  /** Remove attribute node */
  removeAttributeNode(attr: Attr): Attr;
  
  /** Get elements by tag name */
  getElementsByTagName(tagName: string): HTMLCollection;
  
  /** Get elements by class name */
  getElementsByClassName(className: string): HTMLCollection;
  
  /** Query selector (first match) */
  querySelector(selector: string): Element | null;
  
  /** Query selector all (all matches) */
  querySelectorAll(selector: string): NodeList;
  
  /** Check if element matches selector */
  matches(selector: string): boolean;
  
  /** Get closest ancestor matching selector */
  closest(selector: string): Element | null;
  
  /** Insert adjacent element */
  insertAdjacentElement(position: InsertPosition, element: Element): Element | null;
  
  /** Insert adjacent HTML */
  insertAdjacentHTML(position: InsertPosition, html: string): void;
  
  /** Insert adjacent text */
  insertAdjacentText(position: InsertPosition, text: string): void;
  
  /** Attach shadow root */
  attachShadow(init: ShadowRootInit): ShadowRoot;
  
  /** Shadow root if attached */
  readonly shadowRoot: ShadowRoot | null;
}

type InsertPosition = 'beforebegin' | 'afterbegin' | 'beforeend' | 'afterend';

interface ShadowRootInit {
  mode: ShadowRootMode;
  delegatesFocus?: boolean;
}

type ShadowRootMode = 'open' | 'closed';

/**
 * Text node implementation
 */
class Text extends Node {
  /** Text data */
  data: string;
  
  /** Text length */
  readonly length: number;
  
  /** Text content (same as data) */
  textContent: string;
  
  /** Whole text content */
  readonly wholeText: string;
  
  /** Split text at offset */
  splitText(offset: number): Text;
  
  /** Substring data */
  substringData(offset: number, count: number): string;
  
  /** Append data */
  appendData(data: string): void;
  
  /** Insert data */
  insertData(offset: number, data: string): void;
  
  /** Delete data */
  deleteData(offset: number, count: number): void;
  
  /** Replace data */
  replaceData(offset: number, count: number, data: string): void;
}

/**
 * Comment node implementation
 */
class Comment extends Node {
  /** Comment data */
  data: string;
  
  /** Comment length */
  readonly length: number;
  
  /** Substring data */
  substringData(offset: number, count: number): string;
  
  /** Append data */
  appendData(data: string): void;
  
  /** Insert data */
  insertData(offset: number, data: string): void;
  
  /** Delete data */
  deleteData(offset: number, count: number): void;
  
  /** Replace data */
  replaceData(offset: number, count: number, data: string): void;
}

/**
 * Document fragment for efficient DOM manipulation
 */
class DocumentFragment extends Node {
  /** Fragment children */
  readonly children: HTMLCollection;
  
  /** First element child */
  readonly firstElementChild: Element | null;
  
  /** Last element child */
  readonly lastElementChild: Element | null;
  
  /** Child element count */
  readonly childElementCount: number;
  
  /** Get element by ID */
  getElementById(id: string): Element | null;
  
  /** Query selector */
  querySelector(selector: string): Element | null;
  
  /** Query selector all */
  querySelectorAll(selector: string): NodeList;
}

/**
 * Document type declaration node
 */
class DocumentType extends Node {
  /** Document type name */
  readonly name: string;
  
  /** Public ID */
  readonly publicId: string;
  
  /** System ID */
  readonly systemId: string;
}

/**
 * Processing instruction node
 */
class ProcessingInstruction extends Node {
  /** Processing instruction target */
  readonly target: string;
  
  /** Processing instruction data */
  data: string;
}

/**
 * Attribute node implementation
 */
class Attr extends Node {
  /** Attribute name */
  readonly name: string;
  
  /** Attribute value */
  value: string;
  
  /** Owner element */
  readonly ownerElement: Element | null;
  
  /** Specified flag */
  readonly specified: boolean;
}

/**
 * Shadow DOM root implementation
 */
class ShadowRoot extends DocumentFragment {
  /** Shadow root mode */
  readonly mode: ShadrowRootMode;
  
  /** Host element */
  readonly host: Element;
  
  /** Delegates focus flag */
  readonly delegatesFocus: boolean;
  
  /** Inner HTML */
  innerHTML: string;
}

/**
 * Live collection of HTML elements
 */
class HTMLCollection {
  /** Collection length */
  readonly length: number;
  
  /** Get item by index */
  item(index: number): Element | null;
  
  /** Get named item */
  namedItem(name: string): Element | null;
  
  /** Array-like access */
  [index: number]: Element;
}

/**
 * List of nodes (may be live or static)
 */
interface NodeList {
  /** List length */
  readonly length: number;
  
  /** Get item by index */
  item(index: number): Node | null;
  
  /** For each iteration */
  forEach(callback: (node: Node, index: number, list: NodeList) => void): void;
  
  /** Array-like access */
  [index: number]: Node;
}

import { Document } from "happy-dom";

const document = new Document();

// Create elements
const div = document.createElement('div');
div.id = 'container';
div.className = 'main-content';

// Add content
const text = document.createTextNode('Hello World');
div.appendChild(text);

// Query elements
const container = document.getElementById('container');
const divs = document.getElementsByTagName('div');

import { Window } from "happy-dom";

const window = new Window();
const document = window.document;

// Complex DOM structure
document.body.innerHTML = `
  <div class="container">
    <p class="text">Paragraph 1</p>
    <p class="text">Paragraph 2</p>
  </div>
`;

// Query operations
const container = document.querySelector('.container');
const paragraphs = document.querySelectorAll('.text');

// DOM traversal
paragraphs.forEach(p => {
  console.log(p.textContent);
  console.log(p.parentElement === container); // true
});