Detailed explanation of javascriptAPI and case analysis (1)

Method return type description nodeNameString node name nodeValueString node value nodeTypeNumber node type constant value firstChildNode points to the first node in the childNodes list lastChildNode points to the last node childN in the childNodes list...

Method	Return type	Description
NodeName	String	Node name
NodeValue	String	Node Value
NodeType	Number	Type constant value of a node
FirstChild	Node	Point to the first node in the childNodes list
LastChild	Node	Point to the last node in the childNodes list
ChildNodes	NodeList	List of all child nodes
Previussibling	Node	Indicates a forward sibling node. If this node is the first sibling node Point, then the value is null
NextSibling	Node	Point to the next sibling node. If this node is the last sibling node Point, then the value is null
HasChildNodes ()	Boolean	Returns true if childNodes contains one or more nodes.
Attributes	NamedNodeMap	Contains Attr objects that represent the characteristics of an Element. It is only used for Element Node
AppendChild (Node)	Node	SetNodeAdd to the end of childNodes
RemoveChild (Node)	Node	Delete from childNodesNode
ReplaceChild (Newnode,Oldnode)	Node	In childNodesOldnodeReplaceNewnode

 

1 getElementById ()
Note:
1. query the element with the given ID attribute value and return the Element Node of the element. It is also called an element object.
2. Because the id value in an html page is unique, the return value is unique. Therefore, the method name is getElementById () instead of getElementsById ()
3. This method can only be used for document objects, similar to the static keyword of java.
Case:
Var inputDom = document. getElementById ("uname ")
// The attribute value of the current dom object
 
Alert (inputDom. type + inputDom. value + inputDom. id );
// Element node name label name value is null Element Node Type value 1
Alert (inputDom. nodeName + inputDom. nodeType + inputDom. nodeValue );
2. getElementsByName ()
2.1 note:
1. Search for all elements of the given name attribute. This method returns a node set, also known as an object set.
2. This set can be treated as an array. The value of the length attribute indicates the number of sets.
3. Because name cannot uniquely identify an element on an html page, the method name is getElementsByName instead of getElementByName.
Example:



GetElementsByName.html
 






 



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