国产av日韩一区二区三区精品,成人性爱视频在线观看,国产,欧美,日韩,一区,www.成色av久久成人,2222eeee成人天堂

Home Web Front-end JS Tutorial What is DOM (Document Object Modle) in JavaScript

What is DOM (Document Object Modle) in JavaScript

Nov 27, 2024 pm 06:30 PM

What is DOM (Document Object Modle) in JavaScript

The DOM (Document Object Model) is a programming interface for web documents. It represents the structure of a webpage as a tree of objects, where each object corresponds to a part of the page, such as elements, attributes, and text content.

In JavaScript, the DOM allows you to interact with HTML or XML documents programmatically. It enables you to dynamically modify the content, structure, and style of a webpage.

Key Concepts of the DOM:

  1. Document: Refers to the entire web page.
  2. Element: Represents HTML tags such as
    ,

    , , etc.

  3. Node: A basic unit in the DOM tree, which could be an element, text, or attribute.
  4. DOM Tree: A hierarchical structure that represents the webpage as a tree of nodes. The root node is the document, and each HTML element is a node branching from it.

Example of DOM Representation:

For an HTML document like:

<!DOCTYPE html>
<html>
  <head>
    <title>My Page</title>
  </head>
  <body>
    <div>



<p>The DOM for this document might look like this:<br>
</p>

<pre class="brush:php;toolbar:false">Document
 ├── html
     ├── head
     │    └── title
     └── body
          └── div#content
               ├── h1
               └── p

How JavaScript Uses the DOM:

  1. Accessing Elements: JavaScript can select and access elements from the DOM using methods like document.getElementById() or document.querySelector(). 
   let heading = document.getElementById("content");
  1. Manipulating Elements: JavaScript can modify the content, attributes, or style of elements. 
   heading.innerHTML = "New Content";
   heading.style.color = "red";
  1. Event Handling: JavaScript can attach event listeners to DOM elements to respond to user actions like clicks, key presses, etc. 
   document.getElementById("myButton").addEventListener("click", function() {
     alert("Button clicked!");
   });
  1. Creating and Removing Elements: JavaScript can dynamically create new elements or remove existing ones. 
   const newElement = document.createElement("div");
   document.body.appendChild(newElement);

Why the DOM is Important:

  • It provides a way for JavaScript to interact with and manipulate the structure and content of a webpage.
  • It allows for dynamic, interactive web pages without requiring a page reload (e.g., for updating the UI or handling user inputs).

DOM Methods:

Here are some commonly used DOM methods in JavaScript:

  • getElementById(): Selects an element by its ID.
  • querySelector(): Selects the first matching element using a CSS selector.
  • createElement(): Creates a new HTML element.
  • appendChild(): Adds a new child node to an element.
  • removeChild(): Removes a child node from an element.
  • setAttribute(): Sets an attribute on an element.
  • addEventListener(): Attaches an event handler to an element.

Example in Action: 

<!DOCTYPE html>
<html>
  <head>
    <title>My Page</title>
  </head>
  <body>
    <div>



<p>The DOM for this document might look like this:<br>
</p>

<pre class="brush:php;toolbar:false">Document
 ├── html
     ├── head
     │    └── title
     └── body
          └── div#content
               ├── h1
               └── p

In this example, the h1 element is selected, its content is updated, and a click event listener is attached to it. When the heading is clicked, an alert is shown.

The DOM is an essential concept for manipulating the structure of web pages dynamically with JavaScript, and it is fundamental to creating interactive web applications.

The above is the detailed content of What is DOM (Document Object Modle) in JavaScript. For more information, please follow other related articles on the PHP Chinese website!

Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Hot AI Tools

Undress AI Tool

Undress AI Tool

Undress images for free

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use

Zend Studio 13.0.1

Zend Studio 13.0.1

Powerful PHP integrated development environment

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

Java vs. JavaScript: Clearing Up the Confusion Java vs. JavaScript: Clearing Up the Confusion Jun 20, 2025 am 12:27 AM

Java and JavaScript are different programming languages, each suitable for different application scenarios. Java is used for large enterprise and mobile application development, while JavaScript is mainly used for web page development.

Javascript Comments: short explanation Javascript Comments: short explanation Jun 19, 2025 am 12:40 AM

JavaScriptcommentsareessentialformaintaining,reading,andguidingcodeexecution.1)Single-linecommentsareusedforquickexplanations.2)Multi-linecommentsexplaincomplexlogicorprovidedetaileddocumentation.3)Inlinecommentsclarifyspecificpartsofcode.Bestpractic

How to work with dates and times in js? How to work with dates and times in js? Jul 01, 2025 am 01:27 AM

The following points should be noted when processing dates and time in JavaScript: 1. There are many ways to create Date objects. It is recommended to use ISO format strings to ensure compatibility; 2. Get and set time information can be obtained and set methods, and note that the month starts from 0; 3. Manually formatting dates requires strings, and third-party libraries can also be used; 4. It is recommended to use libraries that support time zones, such as Luxon. Mastering these key points can effectively avoid common mistakes.

Why should you place tags at the bottom of the ? Why should you place tags at the bottom of the ? Jul 02, 2025 am 01:22 AM

PlacingtagsatthebottomofablogpostorwebpageservespracticalpurposesforSEO,userexperience,anddesign.1.IthelpswithSEObyallowingsearchenginestoaccesskeyword-relevanttagswithoutclutteringthemaincontent.2.Itimprovesuserexperiencebykeepingthefocusonthearticl

JavaScript vs. Java: A Comprehensive Comparison for Developers JavaScript vs. Java: A Comprehensive Comparison for Developers Jun 20, 2025 am 12:21 AM

JavaScriptispreferredforwebdevelopment,whileJavaisbetterforlarge-scalebackendsystemsandAndroidapps.1)JavaScriptexcelsincreatinginteractivewebexperienceswithitsdynamicnatureandDOMmanipulation.2)Javaoffersstrongtypingandobject-orientedfeatures,idealfor

What is event bubbling and capturing in the DOM? What is event bubbling and capturing in the DOM? Jul 02, 2025 am 01:19 AM

Event capture and bubble are two stages of event propagation in DOM. Capture is from the top layer to the target element, and bubble is from the target element to the top layer. 1. Event capture is implemented by setting the useCapture parameter of addEventListener to true; 2. Event bubble is the default behavior, useCapture is set to false or omitted; 3. Event propagation can be used to prevent event propagation; 4. Event bubbling supports event delegation to improve dynamic content processing efficiency; 5. Capture can be used to intercept events in advance, such as logging or error processing. Understanding these two phases helps to accurately control the timing and how JavaScript responds to user operations.

JavaScript: Exploring Data Types for Efficient Coding JavaScript: Exploring Data Types for Efficient Coding Jun 20, 2025 am 12:46 AM

JavaScripthassevenfundamentaldatatypes:number,string,boolean,undefined,null,object,andsymbol.1)Numbersuseadouble-precisionformat,usefulforwidevaluerangesbutbecautiouswithfloating-pointarithmetic.2)Stringsareimmutable,useefficientconcatenationmethodsf

How can you reduce the payload size of a JavaScript application? How can you reduce the payload size of a JavaScript application? Jun 26, 2025 am 12:54 AM

If JavaScript applications load slowly and have poor performance, the problem is that the payload is too large. Solutions include: 1. Use code splitting (CodeSplitting), split the large bundle into multiple small files through React.lazy() or build tools, and load it as needed to reduce the first download; 2. Remove unused code (TreeShaking), use the ES6 module mechanism to clear "dead code" to ensure that the introduced libraries support this feature; 3. Compress and merge resource files, enable Gzip/Brotli and Terser to compress JS, reasonably merge files and optimize static resources; 4. Replace heavy-duty dependencies and choose lightweight libraries such as day.js and fetch

See all articles