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This article introduces the relevant knowledge of "what does node mean". In the operation process of actual cases, many people will encounter such difficulties. Next, let Xiaobian lead you to learn how to deal with these situations! I hope you can read carefully and learn something!

Node has three meanings: 1. It refers to a network node, which is mainly responsible for sending, receiving and forwarding information in the network;2. It refers to a node in an XML document, and different types of nodes in the document tree are represented by specific Node subinterfaces;3. It refers to Node.js, a js runtime environment based on Chrome V8 engine.

Operating environment: Windows 7 system, nodejs version 10.16.2, Dell G3 computer.

What is node?

Node has many meanings:

1. Network node

A node is a computer or other device connected to a network with an independent address and the ability to transmit or receive data. Nodes can be workstations, clients, network users, or personal computers, as well as servers, printers, and other network-connected devices. Each workstation, server, terminal equipment, network equipment that has its own unique network address is a network node. Network nodes are mainly responsible for sending, receiving and forwarding information in the network. A network node is an interface between a computer and a network. Computers send information to other computers through the network node, and identify and receive information sent by other computers. In a large network, a network node is usually served by a processor or a communication controller. At this time, the network node also has the functions of store-and-forward and path selection. The network adapter used in the local area network also belongs to the network node.

The two endpoints of the network cable are nodes, and the connection relationship between the network cables is established through nodes. In reality, there are many nodes in the network, such as intersections of streets, intersections of rivers, telephone transmission points, electric switches in the power grid, sluice gates in the river network, etc. Nodes can be represented as vertices, endpoints, and associated with network lines.

Node nodes can be workstations, clients, network users, or personal computers, as well as servers, printers, and other network-connected devices.

2. Nodes in XML documents

In DOM (Document Object Model), the hierarchy of HTML documents is represented as a tree structure. The nodes of the tree represent the various contents of the document. The tree representation of an HTML document consists primarily of nodes representing elements or tags (such as and) and nodes identifying text strings. HTML documents also contain nodes that represent html comments. Consider the following simple html document:

a documentis html document

this is adocumnet

If you are unfamiliar with attribute structures in computer programming, it is helpful to know some terms borrowed from their family tree. The node directly above a node is the parent node of that node. Nodes directly below a node are children of that node. Nodes in the same hierarchy with the same parent node are siblings. The collection of nodes in the next hierarchy of a node is the descendants of that node. A node's parent, grandparent, and all other nodes above it are ancestors of that node.

The DOM attribute structure shown in the figure is a tree of NODE objects of various types. The NODE interface defines attributes and methods for convenience and action trees. The childNodes property of the NODE object returns a list of child nodes, and the firstChild, lastChild, nextSibling, previousSibling, and parentNode properties provide methods to traverse the tree. The appendChild(), removeChild(), repleceChild, and inserBefore() methods enable you to add nodes to or remove nodes from the document tree.

the type of node

Different types of nodes in the document tree are represented by specific Node subinterfaces. Each Node object has nodeType attributes that specify the type of node. For example, if a node has nodeType attributes equal to constant attributes, these attributes specify the node's type. For example, if a node's nodeType property equals the constant node.ELEMENT_NODE, you know that the Node object is still an Element object and can use all the methods and properties defined by the Element interface on it.

3、Node.js

Node.js, released in May 2009 and developed by Ryan Dahl, is a JavaScript runtime environment based on Chrome V8 engine, using an event-driven, non-blocking I/O model that allows JavaScript to run on the server-side development platform, making JavaScript an equal scripting language to PHP, Python, Perl, Ruby, and other server-side languages.

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