How to get Dom from JS

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interface	NodeType Quantity	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
DocumentFragment
Attr	Node. Attribute_node	2	node properties

method	description
CreateAttribute ()
Createcomment ()	Creates a new comment node with the specified string.
createelement ()	Creates a new element node with the specified tag name.
createTextNode ()	Creates a new Textnode node with the specified text.
getElementById ()	Returns the element node in the document with the specified ID attribute.
getElementsByTagName ()	Returns all the element nodes in the document with the specified tag name.

"	description
attributes	If the node is an element, the attribute of the element is returned in namednodemap form.
childnodes
FirstChild
LastChild	node Returns the last child node of the current node. Null if there are no child nodes.
nextSibling	Next sibling node
nodename	The name of the node, the element node represents the tag name of the element.
NodeType	class that represents the node Type.
parentnode	parent node of the current node. Null if there is no parent node.
previoussibling	Returns the sibling node, which is close to the current node, before it. If there is no such node, NULL is returned. Previous sibling node

method	description
AppendChild ()
CloneNode ()	copy when The front node, or copy the current node and all its descendants.
HasChildNodes ()	If the current node has child nodes, it returns true.
InsertBefore ()
RemoveChild ()
ReplaceChild ()