This article mainly introduces jspicturesLoading effect example code (delayed loading + waterfall flow loading), which is of great practical value. Friends who need it can refer to it
Mainly do two kinds of image loading effects
One is when there are many pictures on the page, a loading prompt with a reading effect (in order to verify the correct loading, 1 second is set The loading interval of the clock)
The other is to preload the image according to the position of the slider, so as to achieve the loading effect of waterfall flow without the user noticing it
One delayed loading
Main idea:
- ##HTML
- js, read each img in turn, and replace the address in src Go to src and remove the background
- Every time a picture is successfully loaded, the percentage of the progress bar changes accordingly.
- If the loading is unsuccessful, it will prompt an image loading error.
<body>
<p class="picList">
<img class="lazy lazy" src="/static/imghwm/default1.png" data-src="pic/compressed/picList1.jg" alt="Example codes for two effects of js image loading" >
<img class="lazy lazy" src="/static/imghwm/default1.png" data-src="pic/compressed/picList2.jpg" alt="Example codes for two effects of js image loading" >
<img class="lazy lazy" src="/static/imghwm/default1.png" data-src="pic/compressed/picList3.jpg" alt="Example codes for two effects of js image loading" >
<img class="lazy lazy" src="/static/imghwm/default1.png" data-src="pic/compressed/picList4.jpg" alt="Example codes for two effects of js image loading" >
<img class="lazy lazy" src="/static/imghwm/default1.png" data-src="pic/compressed/picList5.jpg" alt="Example codes for two effects of js image loading" >
<img class="lazy lazy" src="/static/imghwm/default1.png" data-src="pic/compressed/picList6.jpg" alt="Example codes for two effects of js image loading" >
<img class="lazy lazy" src="/static/imghwm/default1.png" data-src="pic/compressed/picList7.jpg" alt="Example codes for two effects of js image loading" >
<img class="lazy lazy" src="/static/imghwm/default1.png" data-src="pic/compressed/picList8.jpg" alt="Example codes for two effects of js image loading" >
<img class="lazy lazy" src="/static/imghwm/default1.png" data-src="pic/compressed/picList9.jpg" alt="Example codes for two effects of js image loading" >
<img class="lazy lazy" src="/static/imghwm/default1.png" data-src="pic/compressed/picList10.jpg" alt="Example codes for two effects of js image loading" >
</p>
<p id="loadBar">
<p id="loadBarMask"></p>
</p>
</body>css (scss used , various compatible prefixes will be automatically added when compiling) .picList{
img{
width: 100px;
height: 100px;
position: relative;
/*加载失败时显示灰底文字*/
&:after{
content: "( ⊙ o ⊙ )加载失败";
font-size: 6px;
font-family: FontAwesome;
color: rgb(100, 100, 100);
display: flex;
justify-content: center;
align-items: center;
position: absolute;
top: 0;
left: 0;
width: 100px;
height: 100px;
background-color: #ddd;
}
}
}
.lazy{
background: url(../pic/loading.gif) center no-repeat;
border: 1px solid black;
}
#loadBar{
width: 200px;
height: 15px;
background: linear-gradient(90deg,#187103,#81b50b,#187103);
border: 10px solid white;
position: absolute;
top: 150px;
left: 50%;
margin-left: -100px;
#loadBarMask{
width: 70%;//这个数值显示没有加载成功的图片
height: 100%;
background-color: beige;
position: absolute;
right: 0;
}
}There are two things to pay attention to in css:
- One is displayed when the image is loaded incorrectly The gray background text is placed in the after
- One is the style of the progress bar. The writing is very simple, mainly a layer of green with gradient and a layer of white stacked together. Green means loaded, white means not loaded. When displaying, just control the width of the white layer directly.
var lazyPic = $('img.lazy');
var loadBarMask = $('#loadBarMask');
var picList = $('.picList');
var activePic = 0;
var totalPic = lazyPic.length;
/*每秒加载一张图片*/
function loadPicPerSecond(){
lazyPic.each(function(index){
var self = $(this);
//console.log(self[0].complete);
/*img标签已经事先写在html中，所以此时的complete状态全部都是true*/
setTimeout(function(){
src[index] = self.attr('src');
self.attr('src',src[index]);
self.removeClass('lazy');
//图片获得正确src地址之后，可以执行下面的onload操作
self[0].onload = function(){
//加载读条loadBar动画
countPic();
}
//图片获得的src地址不正确时，执行下面的onerror操作
self[0].onerror = function(){
/*this.style.background = 'url(pic/compressed/picList18.jpg) center no-repeat';*/
countPic();
}
},1000*index);
})
}
/*根据onload的执行情况来计算当前的图片加载进度.每onload一次，activePic就增加1*/
function countPic(){
activePic++;
var leftPic = totalPic - activePic;
var percentPic = Math.ceil(leftPic/totalPic*100);//没有加载的图片百分比，和loadBarMask的宽度占比配合
console.log("已加载"+(100-percentPic)+"%");
loadBarMask.css("width",percentPic+"%");
if(percentPic==0){
$('#loadBar').hide();
}
}
Second waterfall flow loading
- Monitor the window scrolling situation, and when the last picture that has been loaded is about to enter the window, start loading the following pictures.
- Assume that all image addresses already exist in a
- Repeat until all images are loaded.
var lazyPic = $('img.lazy');
var loadBarMask = $('#loadBarMask');
var picList = $('.picList');
var scrollTop,
clientHeight,
scrollHeight;
var threshold = 200; //最后一张图片距离窗口200px的时候开始加载图片
var src = [];
var activePic = 0;
var totalPic = lazyPic.length;
//待加载的图片数据
var dirtSrc = "pic/compressed/picList";
var picData = {imgSrc:[
dirtSrc + "20.jpg",
dirtSrc + "21.jpg",
dirtSrc + "22.jpg",
dirtSrc + "23.jpg",
dirtSrc + "24.jpg",
dirtSrc + "25.jpg",
dirtSrc + "26.jpg",
dirtSrc + "27.jpg",
dirtSrc + "28.jpg",
dirtSrc + "29.jpg",
dirtSrc + "30.jpg",
dirtSrc + "31.jpg",
dirtSrc + "32.jpg",
dirtSrc + "33.jpg",
dirtSrc + "34.jpg",
dirtSrc + "35.jpg",
dirtSrc + "36.jpg",
dirtSrc + "37.jpg",
dirtSrc + "38.jpg",
dirtSrc + "39.jpg",
dirtSrc + "40.jpg",
dirtSrc + "41.jpg",
dirtSrc + "42.jpg",
dirtSrc + "43.jpg",
dirtSrc + "44.jpg",
dirtSrc + "45.jpg",
dirtSrc + "46.jpg",
dirtSrc + "47.jpg",
dirtSrc + "48.jpg",
dirtSrc + "49.jpg",
]};
//加载次数计数器
var scrollIndex = 0;
$(function(){
/*监听窗口滚动情况*/
$(window).on('scroll',function(){
scrollTop = $(window).scrollTop();//$(window).scrollTop()==document.body.scrollTop
clientHeight = $(window).height();
scrollHeight = picList.last().height();//picList.last()[0].clientHeight
/*目标与窗口的距离达到阈值时开始加载*/
if(scrollHeight-clientHeight-scrollTop < threshold){
scrollPic(10);
}
})
})
/*根据滚动程度加载图片，每次加载perAmount张*/
function scrollPic(perAmount = 10){
var totalAmount = perAmount * (scrollIndex+1);
//考虑到最后一次加载的时候，剩余的图片数量有可能达不到限定的每次加载的数量，这时候需要更改totalAmount的值
if(totalAmount>picData.imgSrc.length){
totalAmount = picData.imgSrc.length;
}
for(scrollIndex;scrollIndex<totalAmount;scrollIndex++){
var oimg = new Image();
oimg.src = picData.imgSrc[scrollIndex];
picList.append(oimg);
}
}What is more urgent is the values of scrollTop and height. Object, I always can’t remember clearly, so follow js and jquery is all written down and can be used directly in the future. After figuring out the numerical relationship, the loading can be triggered as long as the conditions are met.
【Related Recommendations】Special Recommendation:"php Programmer Toolbox" V0.1 version Download
2.Free js online video tutorial#3.
php.cn Dugu Jiujian (3) - JavaScript video tutorialThe above is the detailed content of Example codes for two effects of js image loading. For more information, please follow other related articles on the PHP Chinese website!
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.
JavaScript Frameworks: Powering Modern Web DevelopmentMay 02, 2025 am 12:04 AMThe power of the JavaScript framework lies in simplifying development, improving user experience and application performance. When choosing a framework, consider: 1. Project size and complexity, 2. Team experience, 3. Ecosystem and community support.
The Relationship Between JavaScript, C , and BrowsersMay 01, 2025 am 12:06 AMIntroduction I know you may find it strange, what exactly does JavaScript, C and browser have to do? They seem to be unrelated, but in fact, they play a very important role in modern web development. Today we will discuss the close connection between these three. Through this article, you will learn how JavaScript runs in the browser, the role of C in the browser engine, and how they work together to drive rendering and interaction of web pages. We all know the relationship between JavaScript and browser. JavaScript is the core language of front-end development. It runs directly in the browser, making web pages vivid and interesting. Have you ever wondered why JavaScr
Node.js Streams with TypeScriptApr 30, 2025 am 08:22 AMNode.js excels at efficient I/O, largely thanks to streams. Streams process data incrementally, avoiding memory overload—ideal for large files, network tasks, and real-time applications. Combining streams with TypeScript's type safety creates a powe
Python vs. JavaScript: Performance and Efficiency ConsiderationsApr 30, 2025 am 12:08 AMThe differences in performance and efficiency between Python and JavaScript are mainly reflected in: 1) As an interpreted language, Python runs slowly but has high development efficiency and is suitable for rapid prototype development; 2) JavaScript is limited to single thread in the browser, but multi-threading and asynchronous I/O can be used to improve performance in Node.js, and both have advantages in actual projects.
The Origins of JavaScript: Exploring Its Implementation LanguageApr 29, 2025 am 12:51 AMJavaScript originated in 1995 and was created by Brandon Ike, and realized the language into C. 1.C language provides high performance and system-level programming capabilities for JavaScript. 2. JavaScript's memory management and performance optimization rely on C language. 3. The cross-platform feature of C language helps JavaScript run efficiently on different operating systems.
Behind the Scenes: What Language Powers JavaScript?Apr 28, 2025 am 12:01 AMJavaScript runs in browsers and Node.js environments and relies on the JavaScript engine to parse and execute code. 1) Generate abstract syntax tree (AST) in the parsing stage; 2) convert AST into bytecode or machine code in the compilation stage; 3) execute the compiled code in the execution stage.
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
WebStorm Mac version
Useful JavaScript development tools
MinGW - Minimalist GNU for Windows
This project is in the process of being migrated to osdn.net/projects/mingw, you can continue to follow us there. MinGW: A native Windows port of the GNU Compiler Collection (GCC), freely distributable import libraries and header files for building native Windows applications; includes extensions to the MSVC runtime to support C99 functionality. All MinGW software can run on 64-bit Windows platforms.
ZendStudio 13.5.1 Mac
Powerful PHP integrated development environment
Zend Studio 13.0.1
Powerful PHP integrated development environment
EditPlus Chinese cracked version
Small size, syntax highlighting, does not support code prompt function
