jQuery动态追加页面数据以及事件委托详解

我们要执行的任务是页面起初有一部分图片，我们在底下有一个MorePhotos的链接，点击后，

我们要执行的任务是页面起初有一部分图片，我们在底下有一个More Photos的链接，点击后，向当前页面后加载一部分图片，再点击该链接，继续加载，直到将我们列出的页面加载完成，此时该链接也消失了。

首先效果图如下：

这个只截取了最底下的一部分页面。在鼠标悬停在图片上时，还会有文字出现，鼠标移出时文字消失。 我们现在要做的就是点击底下的MorePhotos链接时，再加载一部分数据，然后再点击在加载一部分数据，直到数据加载完。 首先body中代码如下：

<div id = "container">
<h1> Photo Gallery</h1>

<div id = "gallery">
 <div class = "photo">
 <img src = "./images/1.jpg">
 <div class = "details">
 <div class = "description">The Cullin Mountains, Isle of skye ....</div>
 <div class = "date">12/24/2000</div>
 <div class = "photographer"> Alasdair Dougall</div>
 </div>
 </div>

 <div class = "photo">
 <img src = "./images/2.jpg">
 <div class = "details">
 <div class = "description">The Cullin Mountains, Isle of skye.... </div>
 <div class = "date">12/24/2000</div>
 <div class = "photographer"> Alasdair Dougall</div>
 </div>
 </div>

 <div class = "photo">
 <img src = "./images/3.jpg">
 <div class = "details">
 <div class = "description">The Cullin Mountains, Isle of skye.... </div>
 <div class = "date">12/24/2000</div>
 <div class = "photographer"> Alasdair Dougall</div>
 </div>
 </div>
//若干图片

</div>

 <div class = "link"><a id = "more-photos" href = "1.html"> More Photos >></a></div> 
</div>

然后在同一根目录下写几个HTML代码片段，用于加载。

如，我这有一个1.html代码如下

<div class = "photo">
 <img src = "./images/1.jpg">
 <div class = "details">
 <div class = "description">The Cullin Mountains, Isle of skye </div>
 <div class = "date">12/24/2000</div>
 <div class = "photographer"> Alasdair Dougall</div>
 </div>
 </div>

 <div class = "photo">
 <img src = "./images/2.jpg">
 <div class = "details">
 <div class = "description">The Cullin Mountains, Isle of skye </div>
 <div class = "date">12/24/2000</div>
 <div class = "photographer"> Alasdair Dougall</div>
 </div>
 </div>

 <div class = "photo">
 <img src = "./images/3.jpg">
 <div class = "details">
 <div class = "description">The Cullin Mountains, Isle of skye </div>
 <div class = "date">12/24/2000</div>
 <div class = "photographer"> Alasdair Dougall</div>
 </div>
 </div>

 <div class = "photo">
 <img src = "./images/4.jpg">
 <div class = "details">
 <div class = "description">The Cullin Mountains, Isle of skye </div>
 <div class = "date">12/24/2000</div>
 <div class = "photographer"> Alasdair Dougall</div>
 </div>
 </div>

 <div class = "photo">
 <img src = "./images/5.jpg">
 <div class = "details">
 <div class = "description">The Cullin Mountains, Isle of skye </div>
 <div class = "date">12/24/2000</div>
 <div class = "photographer"> Alasdair Dougall</div>
 </div>
 </div>

 <div class = "photo">
 <img src = "./images/6.jpg">
 <div class = "details">
 <div class = "description">The Cullin Mountains, Isle of skye </div>
 <div class = "date">12/24/2000</div>
 <div class = "photographer"> Alasdair Dougall</div>
 </div>
 </div>

在这个HTML片段中我引入了6个图片。其他的片段如2.html等等都可以仿照上面的这个来写。在定义好了许多个HTML片段后，利用jQuery进行动态追加数据。

首先引入一个jquery库 http://libs.baidu.com/jquery/1.9.0/jquery.js

<script>
 $(document).ready(function(){
 //首先定义一个变量来记录当前是多少页
 var pageNum = 1;

 //给链接添加点击事件
 $("#more-photos").click(function(event){
 event.preventDefault();
 var $link = $(this);

 //获得当前所点链接的url
 var url = $link.attr('href');

 //如果该链接的url存在，进行页面追加
 if(url){
 $.get(url, function(data){
 $("#gallery").append(data);
 });

 pageNum ++;
 //总共有十个片段要追加，名称分别为1.html,2.html ...10.html
 当当前页面的总数小于总数时，进行链接更新。
 if(pageNum < 10){
 $link.attr('href', './'+pageNum+'.html');
 }

 //当将所有片段追加完成后，移除链接。
 else{
 $link.remove();
 }
 }
 })
 });

以上的代码就可以进行动态的向页面追加数据了。

但是在谷歌的浏览器中会出现以下的错误：

jquery.js:8475 XMLHttpRequest cannot load file:///C:/Users/%E9%95%BF%E5%AD%99%E4%B8%B9%E5%87%A4/Desktop/webtest/1.html. Cross origin requests are only supported for protocol schemes: http, data, chrome, chrome-extension, https.

在IE10的环境下进行测试的，没问题。

解决办法就是装一个web服务器，然后将文件拷到项目中，以web服务器中的路径访问，就没有问题啦！形如http://localhost:8080/ajax/ajaxLoad.html

由于还有鼠标悬浮事件，当我们将鼠标悬浮在某个图片上时，就会出现文字，移出时，图片上的文字消失。

$(document).ready(function(){
 $('div .photo').hover(function(){
 $(this).find('.details').fadeTo('slow', 0.7);
 },function(){
 $(this).find('.details').fadeOut('slow');
 })
 });

或者可以将上面的代码组合起来减少冗余代码：

$(document).ready(function(){
 $('div.photo').on('mouseenter mouseleave', 
 function(event){
 var $details = $(this).find('.details');
 if(event.type == 'mouseenter'){
 $details.fadeTo('slow', 0.7);
 //0.7代表的是透明度
 }
 else{
 $details.fadeOut('slow');
 }
 })
});

当我们使用上面的两种代码为每个图片添加鼠标悬浮事件时，只有最初页面上的那些图片才会被绑定事件，而经过动态加载的图片上却没能绑定上事件。因为事件处理程序只会添加到调用方法时已经存在的元素上，像通过这种动态追加的元素，不会绑定那些事件。

所以有两种解决方案：

1. 在动态加载后重新绑定事件处理程序 2. 一开始就把事件绑定在存在的元素上，依赖于事件冒泡。

接下来就是使用jquery的委托方法;

$(document).ready(function(){
 $('#gallery').on('mouseenter mouseleave', 'div.photo', function(event){

 var $details = $(this).find('.details');
 if(event.type == 'mouseenter'){
 $details.fadeTo('slow', 0.7);
 }
 else{
 $details.fadeOut('slow');
 }
 })
 })

$(‘#gallery').on(‘mouseenter mouseleave', ‘div.photo', function(event)中，在将'div.photo'作为第二个参数的情况下，.on()方法会把 this映射到 gallery中与该选择符匹配的元素。换句话说，就是this指向gallery中的 div class= ‘photo'的元素。

所以在最后追加的页面中，由于都属于gallery 下的元素，所以每一个图片都会加上相应的事件。

或许在你不知道要添加的页面属于哪个父级元素的话，可以将$(‘#gallery').on( )中的'#gallery'替换成document。这样就不必担心选错容器。因为document是页面中所有元素的祖先。

但使用document有弊端：

当DOM嵌套结构很深，事件冒泡通过大量的祖先元素会有较大的性能损失。 但是还会有其他的原因让我们选择document作为委托作用域。 一般来说，只有当相应的DOM元素加载完毕，才会给它绑定事件处理程序。这就是为什么我们要把代码放到$(document).ready(function(){}内部的原因。可是document元素是随着页面加载几乎就立即可以调用的。把处理程序绑定到document不用等到完整的DOM构建结束。如上面的代码可以写为：‘

(function($){
 $(document).on('mouseenter mouseleave', 'div.photo', function(event){

 var $details = $(this).find('.details');
 if(event.type == 'mouseenter'){
 $details.fadeTo('slow', 0.7);
 }
 else{
 $details.fadeOut('slow');
 }
 })
 })(jQuery);

因为没有等到整个文档就绪，所以可以确保所有<div class= 'photo'>元素只要呈现在页面上，就可以应用mouseenter 和mouseleave行为。

上面就是关于利用jQuery动态追加页面数据以及事件委托的全部知识。下面附上源代码；

<!DOCTYPE html>
<html>
<head>
<meta charset = "utf-8" />
 <title>动态加载</title>
 <script type="text/javascript" src = "http://libs.baidu.com/jquery/1.9.0/jquery.js"></script>
 <style type="text/css">
 *{
 margin: 0px;
 padding: 0px;
 }


 #container{
 position: relative;
 width: 1300px;
 margin: 0 auto;
 /*background-color: #ccc;
 height: auto;*/
 }
 #gallery{
 position: relative;
 width: 1300px;
 margin: 0 auto;

 }
 .details{
 display: none;
 }

 .photo{
 padding: 20px;
 border-radius: 5px;
 border:1px solid #ccc;
 box-shadow: 0 0 5px #ccc;
 float: left;
 margin: 8px;
 }

 .photo img{

 /*z-index: 1;*/
 width: 200px;
 height: 300px;
 clear: both;
 }

 .photo .details{
 position: absolute;
 z-index: 2;
 padding-left: 20px;
 margin-top:-200px;
 /*clear: both;*/
 overflow: hidden;
 }
 .description{
 overflow: hidden;
 width: 200px;
 color: lightgreen;
 font-size: 18px;
 font-weight: bold;
 }

 .date{
 font-size:16px;
 margin: 20px 0px;
 color: red; 
 }
 .photographer{
 font-size:14px;
 font-family: "Arial" ;
 }
 .link a{

 clear: both;
 text-decoration: none;
 padding-left: 90%;


 }
 h1{
 text-align: center; 
 }
 </style>

 <script>
 $(document).ready(function(){

 var pageNum = 1;
 $("#more-photos").click(function(event){
 event.preventDefault();
 var $link = $(this);
 var url = $link.attr('href');
 console.log(url);
 if(url){
 $.get(url, function(data){
 $("#gallery").append(data);
 });

 pageNum ++;
 if(pageNum < 4){
 $link.attr('href', './'+pageNum+'.html');
 }


 else{
 $link.remove();
 }
 }
 })
 })

 // $(document).ready(function(){
 // $('div .photo').hover(function(){
 // $(this).find('.details').fadeTo('slow', 0.7);
 // },function(){
 // $(this).find('.details').fadeOut('slow');
 // })
 // })

 $(document).ready(function(){
 $('#gallery').on('mouseenter mouseleave', 'div.photo', function(event){

 var $details = $(this).find('.details');
 if(event.type == 'mouseenter'){
 $details.fadeTo('slow', 0.7);
 }
 else{
 $details.fadeOut('slow');
 }
 })
 })

 </script>
</head>
<body>
<div id = "container">
<h1> Photo Gallery</h1>

<div id = "gallery">
 <div class = "photo">
 <img src = "./images/1.jpg">
 <div class = "details">
 <div class = "description">The Cullin Mountains, Isle of skye ....</div>
 <div class = "date">12/24/2000</div>
 <div class = "photographer"> Alasdair Dougall</div>
 </div>
 </div>

 <div class = "photo">
 <img src = "./images/2.jpg">
 <div class = "details">
 <div class = "description">The Cullin Mountains, Isle of skye.... </div>
 <div class = "date">12/24/2000</div>
 <div class = "photographer"> Alasdair Dougall</div>
 </div>
 </div>

 <div class = "photo">
 <img src = "./images/3.jpg">
 <div class = "details">
 <div class = "description">The Cullin Mountains, Isle of skye.... </div>
 <div class = "date">12/24/2000</div>
 <div class = "photographer"> Alasdair Dougall</div>
 </div>
 </div>

 <div class = "photo">
 <img src = "./images/4.jpg">
 <div class = "details">
 <div class = "description">The Cullin Mountains, Isle of skye .....</div>
 <div class = "date">12/24/2000</div>
 <div class = "photographer"> Alasdair Dougall</div>
 </div>
 </div>

 <div class = "photo">
 <img src = "./images/5.jpg">
 <div class = "details">
 <div class = "description">The Cullin Mountains, Isle of skye ....</div>
 <div class = "date">12/24/2000</div>
 <div class = "photographer"> Alasdair Dougall</div>
 </div>
 </div>

 <div class = "photo">
 <img src = "./images/6.jpg">
 <div class = "details">
 <div class = "description">The Cullin Mountains, Isle of skye ...</div>
 <div class = "date">12/24/2000</div>
 <div class = "photographer"> Alasdair Dougall</div>
 </div>
 </div>

 <div class = "photo">
 <img src = "./images/7.jpg">
 <div class = "details">
 <div class = "description">The Cullin Mountains, Isle of skye.... </div>
 <div class = "date">12/24/2000</div>
 <div class = "photographer"> Alasdair Dougall</div>
 </div>
 </div>

 <div class = "photo">
 <img src = "./images/8.jpg">
 <div class = "details">
 <div class = "description">The Cullin Mountains, Isle of skye..... </div>
 <div class = "date">12/24/2000</div>
 <div class = "photographer"> Alasdair Dougall</div>
 </div>
 </div>

 <div class = "photo">
 <img src = "./images/9.jpg">
 <div class = "details">
 <div class = "description">The Cullin Mountains, Isle of skye ...... </div>
 <div class = "date">12/24/2000</div>
 <div class = "photographer"> Alasdair Dougall</div>
 </div>
 </div>

 <div class = "photo">
 <img src = "./images/10.jpg">
 <div class = "details">
 <div class = "description">The Cullin Mountains, Isle of skye </div>
 <div class = "date">12/24/2000</div>
 <div class = "photographer"> Alasdair Dougall</div>
 </div>
 </div>

 <div class = "photo">
 <img src = "./images/11.jpg">
 <div class = "details">
 <div class = "description">The Cullin Mountains, Isle of skye </div>
 <div class = "date">12/24/2000</div>
 <div class = "photographer"> Alasdair Dougall</div>
 </div>
 </div>

 <div class = "photo">
 <img src = "./images/12.jpg">
 <div class = "details">
 <div class = "description">The Cullin Mountains, Isle of skye </div>
 <div class = "date">12/24/2000</div>
 <div class = "photographer"> Alasdair Dougall</div>
 </div>
 </div>


 <div class = "photo">
 <img src = "./images/13.jpg">
 <div class = "details">
 <div class = "description">The Cullin Mountains, Isle of skye </div>
 <div class = "date">12/24/2000</div>
 <div class = "photographer"> Alasdair Dougall</div>
 </div>
 </div>

 <div class = "photo">
 <img src = "./images/14.jpg">
 <div class = "details">
 <div class = "description">The Cullin Mountains, Isle of skye </div>
 <div class = "date">12/24/2000</div>
 <div class = "photographer"> Alasdair Dougall</div>
 </div>
 </div>

 <div class = "photo">
 <img src = "./images/15.jpg">
 <div class = "details">
 <div class = "description">The Cullin Mountains, Isle of skye </div>
 <div class = "date">12/24/2000</div>
 <div class = "photographer"> Alasdair Dougall</div>
 </div>
 </div>

</div>

 <div class = "link"><a id = "more-photos" href = "1.html"> More Photos >></a></div> 
</div>
</body>
</html>

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。

jQuery动态追加页面数据 jQuery事件委托 jQuery追加页面数据