What are the exceptions for events that cannot bubble?
Exceptions for bubbling events: What events cannot bubble?
In most cases, events in web pages can be delivered and processed through the bubbling mechanism. However, in some cases, some special events cannot be bubbled. This article will introduce some common events that cannot be bubbled and provide code examples to help readers better understand.
-
focusandblurevents: These two events involve focus changes of elements. When an element gains focus, thefocusevent is triggered; when the element loses focus, theblurevent is triggered. Because the focus change occurs on a specific element, not its parent or other descendant elements, these two events cannot bubble up.
The following is a sample code. When the input box gets focus, the event cannot be captured using bubbling events:
<!DOCTYPE html>
<html>
<head>
<title>Focus and Blur Event</title>
</head>
<body>
<div>
<input type="text" id="myInput">
</div>
<script>
var myInput = document.getElementById("myInput");
myInput.addEventListener("focus", function(){
console.log("Input has focus");
});
document.body.addEventListener("focus", function(){
console.log("Focus event bubbled");
}, true);
// 输出结果：
// Input has focus
</script>
</body>
</html>In the above code, when the input box gets focus , only the focus event will be triggered, and the focus event that bubbles up to the body element will not be triggered.
mouseenterandmouseleaveevents: These two events are used to detect when the cursor enters or leaves the bounds of an element. Unlike themouseoverandmouseoutevents, themouseenterandmouseleaveevents do not bubble to parent or descendant elements.
Below is a sample code, when the mouse enters or leaves the div element, these two events cannot be captured through bubbling events:
<!DOCTYPE html>
<html>
<head>
<title>Mouse Enter and Leave Event</title>
<style>
#myDiv {
width: 100px;
height: 100px;
background-color: red;
}
</style>
</head>
<body>
<div id="myDiv"></div>
<script>
var myDiv = document.getElementById("myDiv");
myDiv.addEventListener("mouseenter", function(){
console.log("Mouse entered the div");
});
document.body.addEventListener("mouseenter", function(){
console.log("Mouse entered the body");
}, true);
// 输出结果：
// Mouse entered the div
</script>
</body>
</html> above In the code, when the mouse enters the div element, only the mouseenter event will be triggered, and the mouseenter event that bubbles to the body element will not be triggered. event.
In summary, focus, blur, mouseenter and mouseleave events cannot be delivered through the bubbling mechanism and processing. Understanding and distinguishing these special events is one of the essential knowledge as a front-end developer.
The above is the detailed content of What are the exceptions for events that cannot bubble?. For more information, please follow other related articles on the PHP Chinese website!
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
AI Hentai Generator
Generate AI Hentai for free.
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Hot Topics
Replace String Characters in JavaScript
Mar 11, 2025 am 12:07 AM
Detailed explanation of JavaScript string replacement method and FAQ This article will explore two ways to replace string characters in JavaScript: internal JavaScript code and internal HTML for web pages. Replace string inside JavaScript code The most direct way is to use the replace() method: str = str.replace("find","replace"); This method replaces only the first match. To replace all matches, use a regular expression and add the global flag g: str = str.replace(/fi
8 Stunning jQuery Page Layout Plugins
Mar 06, 2025 am 12:48 AM
Leverage jQuery for Effortless Web Page Layouts: 8 Essential Plugins jQuery simplifies web page layout significantly. This article highlights eight powerful jQuery plugins that streamline the process, particularly useful for manual website creation
Build Your Own AJAX Web Applications
Mar 09, 2025 am 12:11 AM
So here you are, ready to learn all about this thing called AJAX. But, what exactly is it? The term AJAX refers to a loose grouping of technologies that are used to create dynamic, interactive web content. The term AJAX, originally coined by Jesse J
10 Mobile Cheat Sheets for Mobile Development
Mar 05, 2025 am 12:43 AM
This post compiles helpful cheat sheets, reference guides, quick recipes, and code snippets for Android, Blackberry, and iPhone app development. No developer should be without them! Touch Gesture Reference Guide (PDF) A valuable resource for desig
Improve Your jQuery Knowledge with the Source Viewer
Mar 05, 2025 am 12:54 AM
jQuery is a great JavaScript framework. However, as with any library, sometimes it’s necessary to get under the hood to discover what’s going on. Perhaps it’s because you’re tracing a bug or are just curious about how jQuery achieves a particular UI
10 jQuery Fun and Games Plugins
Mar 08, 2025 am 12:42 AM
10 fun jQuery game plugins to make your website more attractive and enhance user stickiness! While Flash is still the best software for developing casual web games, jQuery can also create surprising effects, and while not comparable to pure action Flash games, in some cases you can also have unexpected fun in your browser. jQuery tic toe game The "Hello world" of game programming now has a jQuery version. Source code jQuery Crazy Word Composition Game This is a fill-in-the-blank game, and it can produce some weird results due to not knowing the context of the word. Source code jQuery mine sweeping game
How do I create and publish my own JavaScript libraries?
Mar 18, 2025 pm 03:12 PM
Article discusses creating, publishing, and maintaining JavaScript libraries, focusing on planning, development, testing, documentation, and promotion strategies.
jQuery Parallax Tutorial - Animated Header Background
Mar 08, 2025 am 12:39 AM
This tutorial demonstrates how to create a captivating parallax background effect using jQuery. We'll build a header banner with layered images that create a stunning visual depth. The updated plugin works with jQuery 1.6.4 and later. Download the
