How to Get dom using js

Interface	NodeType constant	NodeType Value	Remarks
Element	Node. ELEMENT_NODE	1	Element Node
Text	Node. TEXT_NODE	3	Text Node
Document	Node. DOCUMENT_NODE	9	Document
Comment	Node. COMMENT_NODE	8	Annotated text
DocumentFragment	Node. DOCUMENT_FRAGMENT_NODE	11	Document parts
Attr	Node. ATTRIBUTE_NODE	2	Node attributes

Method	Description
CreateAttribute ()	Create a new Attr node with the specified name.
CreateComment ()	Creates a Comment node with the specified string.
CreateElement ()	Create an Element node with the specified tag name.
CreateTextNode ()	Creates a TextNode with the specified text.
GetElementById ()	Return the Element node with the specified id attribute in the document.
GetElementsByTagName ()	Returns all Element nodes with the specified tag name in the document.

Attribute	Description
Attributes	If the node is an Element, the attribute of the Element is returned in the form of NamedNodeMap.
ChildNodes	Store the subnodes of the current Node in the form of Node. If no child node exists, an empty array is returned.
FirstChild	Return the first subnode of the current Node as a Node. If no subnode exists, the value is null.
LastChild	Return the last subnode of the current Node as a Node. If no subnode exists, the value is null.
NextSibling	Return the sibling Node of the current Node in the form of Node. If no such node exists, null is returned.Next sibling Node
NodeName	The name of the node. The Element node represents the Tag Name of the Element.
NodeType	Indicates the node type.
ParentNode	ReturnsParent node. If no parent node exists, the value is null.
Previussibling	Return the sibling Node next to the current Node and before it in the form of Node. If no such node exists, null is returned.Previous sibling Node

Method	Description
AppendChild ()	Add a node to the childNodes [] Group of the current node to add a node to the document tree.
CloneNode ()	Copy the current node or all its child nodes.
HasChildNodes ()	If the current node has a subnode, true is returned.
InsertBefore ()	Insert a node to the document tree before the specified child node of the current node. If the node already exists, delete it and insert it to its location.
RemoveChild ()	Delete the child node from the document tree and return the specified child node.
ReplaceChild ()	Delete the child node from the document tree, return the specified child node, and replace it with another node.