Web Front-endJS TutorialDOM event stage and event capture and event bubbling execution sequence (detailed graphic and text explanation)_jqueryDOM event stage and event capture and event bubbling execution sequence (detailed graphic and text explanation)_jquery
As the saying goes, a good memory is not as good as a bad pen. If you don’t thoroughly understand so many technical articles, it will be easy to forget the technical points quickly. Below are the technical articles that the editor usually browses, and the notes I compiled to share with you.
During the development process, we all hope to use other people’s mature frameworks, because standing on the shoulders of giants will greatly improve the efficiency of our development. However, we should also and must understand its basic principles. For example, for DOM events, the jquery framework helps us encapsulate and abstract the different behaviors of various browsers, bringing great convenience to event processing. However, browsers are gradually becoming unified and standardized, and we can use official standardized interfaces more safely. Because only by winning the hearts and minds of many developers can the browser go further. Just like when we use a lower version browser to open certain pages, we will be told to use an advanced browser such as Chrome to access it. But this is a revolutionary process. In order to make our webPage better serve more people, we now have to be better compatible with these historical issues. To be compatible, in addition to relying on the framework, we must understand its basic principles.
Three stages of DOM events
When a DOM event is triggered, it is not simply triggered once on the object itself, but will go through three different stages:
1. Capture phase : First, go from the root node document of the document to the event trigger object, and capture the event object from the outside in;
2. Target stage : Arrive at the target event location (where the incident occurred) and trigger the event;
3. Bubble stage : Then trace back from the target event location to the root node of the document, and bubble the event object from the inside out.
Citation source: http://www.w3.org/TR/DOM-Level-3-Events/#event-flow
The order of event capture and event bubbling is obvious.
Experimental part
Open the online editor: http://jsbin.com/goqede/edit?html,css,js,output
The code is as follows:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-">
<title>Document</title>
<style>
#outer{
text-align: center;
width: px;
height: px;
background-color: #ccc;
margin: auto;
}
#middle{
width: px;
height: px;
background-color: #f;
margin: auto;
}
#inner{
width: px;
height: px;
background-color: #f;
margin: auto;
border-rad
}
</style>
</head>
<body>
<div id='outer'>
<span>outer</span>
<div id='middle'>
<span>middle</span>
<div id='inner'>
<span>inner</span>
</div>
</div>
</div>
<script>
function $(element){
return document.getElementById(element);
}
function on(element,event_name,handler,use_capture){
if(addEventListener){
$(element).addEventListener(event_name,handler,use_capture);
}
else{
$(element).attachEvent('on'+event_name,handler);
}
}
on("outer","click",o_click_c,true);
on("middle","click",m_click_c,true);
on("inner","click",i_click_c,true);
on("outer","click",o_click_b,false);
on("middle","click",m_click_b,false);
on("inner","click",i_click_b,false);
function o_click_c(){
console.log("outer_捕获");
alert("outer_捕获");
}
function m_click_c(){
console.log("middle_捕获")
alert("middle_捕获");
}
function i_click_c(){
console.log("inner_捕获")
alert("inner_捕获");
}
function o_click_b(){
console.log("outer_冒泡")
alert("outer_冒泡");
}
function m_click_b(){
console.log("middle_冒泡")
alert("middle_冒泡");
}
function i_click_b(){
console.log("inner_冒泡")
alert("inner_冒泡");
}
</script>
</body>
</html>
When we click inner the result is:
outer_capture
middle_capture
inner_capture
inner_bubble
middle_bubble
outer_bubble
It can be seen that the event is captured from the outside inward first, until the event element is reached, and then bubbles up to the root node from the inside out
tips:
When an event is triggered in the target stage, it will be executed according to the order of event registration. The order of registration in the other two stages does not affect the order of event execution. That is to say, if both bubbling events and capture events are registered here, they will be executed in the order of registration.
For example, when I click inner, according to the above order, the answer is indeed the answer we want:
,
When my event registration sequence is changed to the following code:
When we click outer:
When we click on middle:
When we click inner:
It can be seen that the order of event execution on the event element in the target stage is determined by the order of event registration
The above content is the DOM event stage and the execution sequence of event capture and event bubbling in this article (detailed pictures and texts). I hope it will be helpful to everyone's future work and study.
Javascript Data Types : Is there any difference between Browser and NodeJs?May 14, 2025 am 12:15 AMJavaScript core data types are consistent in browsers and Node.js, but are handled differently from the extra types. 1) The global object is window in the browser and global in Node.js. 2) Node.js' unique Buffer object, used to process binary data. 3) There are also differences in performance and time processing, and the code needs to be adjusted according to the environment.
JavaScript Comments: A Guide to Using // and /* */May 13, 2025 pm 03:49 PMJavaScriptusestwotypesofcomments:single-line(//)andmulti-line(//).1)Use//forquicknotesorsingle-lineexplanations.2)Use//forlongerexplanationsorcommentingoutblocksofcode.Commentsshouldexplainthe'why',notthe'what',andbeplacedabovetherelevantcodeforclari
Python vs. JavaScript: A Comparative Analysis for DevelopersMay 09, 2025 am 12:22 AMThe main difference between Python and JavaScript is the type system and application scenarios. 1. Python uses dynamic types, suitable for scientific computing and data analysis. 2. JavaScript adopts weak types and is widely used in front-end and full-stack development. The two have their own advantages in asynchronous programming and performance optimization, and should be decided according to project requirements when choosing.
Python vs. JavaScript: Choosing the Right Tool for the JobMay 08, 2025 am 12:10 AMWhether to choose Python or JavaScript depends on the project type: 1) Choose Python for data science and automation tasks; 2) Choose JavaScript for front-end and full-stack development. Python is favored for its powerful library in data processing and automation, while JavaScript is indispensable for its advantages in web interaction and full-stack development.
Python and JavaScript: Understanding the Strengths of EachMay 06, 2025 am 12:15 AMPython and JavaScript each have their own advantages, and the choice depends on project needs and personal preferences. 1. Python is easy to learn, with concise syntax, suitable for data science and back-end development, but has a slow execution speed. 2. JavaScript is everywhere in front-end development and has strong asynchronous programming capabilities. Node.js makes it suitable for full-stack development, but the syntax may be complex and error-prone.
JavaScript's Core: Is It Built on C or C ?May 05, 2025 am 12:07 AMJavaScriptisnotbuiltonCorC ;it'saninterpretedlanguagethatrunsonenginesoftenwritteninC .1)JavaScriptwasdesignedasalightweight,interpretedlanguageforwebbrowsers.2)EnginesevolvedfromsimpleinterpreterstoJITcompilers,typicallyinC ,improvingperformance.
JavaScript Applications: From Front-End to Back-EndMay 04, 2025 am 12:12 AMJavaScript can be used for front-end and back-end development. The front-end enhances the user experience through DOM operations, and the back-end handles server tasks through Node.js. 1. Front-end example: Change the content of the web page text. 2. Backend example: Create a Node.js server.
Python vs. JavaScript: Which Language Should You Learn?May 03, 2025 am 12:10 AMChoosing Python or JavaScript should be based on career development, learning curve and ecosystem: 1) Career development: Python is suitable for data science and back-end development, while JavaScript is suitable for front-end and full-stack development. 2) Learning curve: Python syntax is concise and suitable for beginners; JavaScript syntax is flexible. 3) Ecosystem: Python has rich scientific computing libraries, and JavaScript has a powerful front-end framework.
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
SublimeText3 English version
Recommended: Win version, supports code prompts!
DVWA
Damn Vulnerable Web App (DVWA) is a PHP/MySQL web application that is very vulnerable. Its main goals are to be an aid for security professionals to test their skills and tools in a legal environment, to help web developers better understand the process of securing web applications, and to help teachers/students teach/learn in a classroom environment Web application security. The goal of DVWA is to practice some of the most common web vulnerabilities through a simple and straightforward interface, with varying degrees of difficulty. Please note that this software
Dreamweaver Mac version
Visual web development tools
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
