firefo xml reading and writing to implement js code_javascript skills
Step 1: Convert the xml file into a DOM structure
1
var xmlDoc = document.implementation.createDocument("", "test" , null);
xmlDoc.load("d:\develop\bookmarks.xml");
2
var req = new XMLHttpRequest();
req.open("GET", " chrome://passwdmaker/content/people.xml", false);
req.send(null);
var dom = req.responseXML;
dom is the DOM structure object
Step 2 : Convert DOM structure into xml string
var serializer = Components.classes["@mozilla.org/xmlextras/xmlserializer;1"].createInstance(Components.interfaces.nsIDOMSerializer);
var str = serializer. serializeToString(dom);
str is the string of xml content
2. Write the xml string into an xml file
// str is the xml string
var parser = new DOMParser ();
var dom = parser.parseFromString(str, "text/xml");
var serializer = Components.classes["@mozilla.org/xmlextras/xmlserializer;1"].createInstance(Components. interfaces.nsIDOMSerializer);
var foStream = Components.classes["@mozilla.org/network/file-output-stream;1"].createInstance(Components.interfaces.nsIFileOutputStream);
var file = Components. classes["@mozilla.org/file/local;1"].createInstance(Components.interfaces.nsILocalFile);
file.initWithPath("d:\develop\myxmlfile.xml");// Maintained location
foStream.init(file, 0x02 | 0x08 | 0x20, 0664, 0); // write, create, truncate
serializer.serializeToStream(dom.documentElement, foStream, ""); // rememeber, dom is the DOM tree
foStream.close();
Attachments:
1 Create DOM structure
// Generate document object
var xmldoc = document.implementation.createDocument("","",null );
// Create the header of the xml file
//
var head = xmldoc.createProcessingInstruction("xml","version="1.0" encoding="UTF-8" standalone=" yes"");
xmldoc.appendChild(head);
// Create ROOT node
var nodest = xmldoc.createElement("nodeset");
xmldoc.appendChild(nodest);
//Create child node
var elem1 = doc.createElement("name");
elem1.textContent = "Zhang San";
nodest.appendChild(elem1);
var elem2 = doc .createElement("name");
elem2.textContent = "李思";
nodest.appendChild(elem2);
// The created result is as follows
The xmlDOM structure generated in this way will not be automatically indented when it is converted into an xml string through serialization, but it can be parsed through XML objects.
var serializer = Components.classes["@mozilla.org/xmlextras/xmlserializer;1"].createInstance(Components.interfaces.nsIDOMSerializer);
// Parse DOMxml structure into xml string
// To successfully parse the XML object, the xml header must be removed
// Remove the xml header
var xmlDeclaration = /^] ?>/;
var str = new XML( serializer.serializeToString(xmldoc). replace(xmlDeclaration, '') ).toXMLString();
Haha, now str is an xml string that can be automatically indented. However, if you want your xml to be successfully encoded, you must add the xml header in front of str. Don't forget it.

The main uses of JavaScript in web development include client interaction, form verification and asynchronous communication. 1) Dynamic content update and user interaction through DOM operations; 2) Client verification is carried out before the user submits data to improve the user experience; 3) Refreshless communication with the server is achieved through AJAX technology.

Understanding how JavaScript engine works internally is important to developers because it helps write more efficient code and understand performance bottlenecks and optimization strategies. 1) The engine's workflow includes three stages: parsing, compiling and execution; 2) During the execution process, the engine will perform dynamic optimization, such as inline cache and hidden classes; 3) Best practices include avoiding global variables, optimizing loops, using const and lets, and avoiding excessive use of closures.

Python is more suitable for beginners, with a smooth learning curve and concise syntax; JavaScript is suitable for front-end development, with a steep learning curve and flexible syntax. 1. Python syntax is intuitive and suitable for data science and back-end development. 2. JavaScript is flexible and widely used in front-end and server-side programming.

Python and JavaScript have their own advantages and disadvantages in terms of community, libraries and resources. 1) The Python community is friendly and suitable for beginners, but the front-end development resources are not as rich as JavaScript. 2) Python is powerful in data science and machine learning libraries, while JavaScript is better in front-end development libraries and frameworks. 3) Both have rich learning resources, but Python is suitable for starting with official documents, while JavaScript is better with MDNWebDocs. The choice should be based on project needs and personal interests.

The shift from C/C to JavaScript requires adapting to dynamic typing, garbage collection and asynchronous programming. 1) C/C is a statically typed language that requires manual memory management, while JavaScript is dynamically typed and garbage collection is automatically processed. 2) C/C needs to be compiled into machine code, while JavaScript is an interpreted language. 3) JavaScript introduces concepts such as closures, prototype chains and Promise, which enhances flexibility and asynchronous programming capabilities.

Different JavaScript engines have different effects when parsing and executing JavaScript code, because the implementation principles and optimization strategies of each engine differ. 1. Lexical analysis: convert source code into lexical unit. 2. Grammar analysis: Generate an abstract syntax tree. 3. Optimization and compilation: Generate machine code through the JIT compiler. 4. Execute: Run the machine code. V8 engine optimizes through instant compilation and hidden class, SpiderMonkey uses a type inference system, resulting in different performance performance on the same code.

JavaScript's applications in the real world include server-side programming, mobile application development and Internet of Things control: 1. Server-side programming is realized through Node.js, suitable for high concurrent request processing. 2. Mobile application development is carried out through ReactNative and supports cross-platform deployment. 3. Used for IoT device control through Johnny-Five library, suitable for hardware interaction.

I built a functional multi-tenant SaaS application (an EdTech app) with your everyday tech tool and you can do the same. First, what’s a multi-tenant SaaS application? Multi-tenant SaaS applications let you serve multiple customers from a sing


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