


Example analysis of the method of adding DOM nodes to the document using javascript
This article mainly introduces the method of adding DOM nodes to documents in JavaScript, and compares and analyzes the two methods of node creation in JavaScript, involving related techniques of JavaScript node operation and running time calculation. Friends in need can refer to it. The details are as follows:
Here are two methods compared: the first one: create all nodes first, and then add them to the running time of the document; the second one: first add an empty container to the document, and then add each The running time of creating a node and then adding it to the container. From the test point of view, the second method is better than the first!
The operation effect is shown in the figure below:
The specific code is as follows:
<html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=gb2312" /> <title>将DOM节点添加到文档实例</title> </head> <script type="text/javascript"> //第一种:先创建所有节点,再添加到文档 function createAdd(count) { var start=new Date(); var container=document.createElement("p"); var obj=document.getElementById("main"); for(var i=0;i<count;i++) { var node=document.createElement("p"); node.style.position="absolute"; node.style.left=(6+parseInt(Math.random()*100))+"px"; node.style.top=(6+parseInt(Math.random()*100))+"px"; container.appendChild(node); } obj.appendChild(container); var end=new Date(); var duration=end-start; alert("第一种方式:"+duration+"ms"); } //第二种:先添加到文档一个空容器,再创建所有接点,并分别添加到容器中 function addCreate(count) { var start=new Date(); var container=document.createElement("p"); var obj=document.getElementById("main"); obj.appendChild(container); for(var i=0;i<count;i++) { var node=document.createElement("p"); node.style.position="absolute"; node.style.left=(6+parseInt(Math.random()*100))+"px"; node.style.top=(6+parseInt(Math.random()*100))+"px"; container.appendChild(node); } var end=new Date(); var duration=end-start; alert("第二种方式:"+duration+"ms"); } //检测输入的数据是否正确 function checkData() { var number=parseInt(document.getElementById("count").value); return number; } //调用createAdd()函数 function callCreateAdd() { var count=checkData(); createAdd(count); } //调用addCreate()函数 function callAddCreate() { var count=checkData(); addCreate(count); } </script> <body> <h3 id="将DOM节点添加到文档实例">将DOM节点添加到文档实例</h3> <hr style="border:1px solid #000000;" /> 请输入一个整数: <input type="text" id="count" name="count" /> <br /> <input type="button" id="createadd" name="createadd" value="第一种:先创建所有节点,再添加到文档方式的运行时长" onClick="callCreateAdd();" /> <input type="button" id="one" name="one" value="第二种:先向文档添加一个空容器,然后每创建一个节点,再添加到容器中方式的运行时长" onClick="callAddCreate();" /> <br /> <p id="main" style="position:absolute;"></p> </body> </html>
The above is the entire content of this chapter, more For related tutorials, please visit JavaScript Video Tutorial!

Python is more suitable for data science and automation, while JavaScript is more suitable for front-end and full-stack development. 1. Python performs well in data science and machine learning, using libraries such as NumPy and Pandas for data processing and modeling. 2. Python is concise and efficient in automation and scripting. 3. JavaScript is indispensable in front-end development and is used to build dynamic web pages and single-page applications. 4. JavaScript plays a role in back-end development through Node.js and supports full-stack development.

C and C play a vital role in the JavaScript engine, mainly used to implement interpreters and JIT compilers. 1) C is used to parse JavaScript source code and generate an abstract syntax tree. 2) C is responsible for generating and executing bytecode. 3) C implements the JIT compiler, optimizes and compiles hot-spot code at runtime, and significantly improves the execution efficiency of JavaScript.

JavaScript's application in the real world includes front-end and back-end development. 1) Display front-end applications by building a TODO list application, involving DOM operations and event processing. 2) Build RESTfulAPI through Node.js and Express to demonstrate back-end applications.

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.


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