jquery-2 jQuery原理和核心方法（多看学习视频）

时间 2020-05-22

原文原文链接

jquery-2 jQuery原理和核心方法（多看学习视频）

1、总结

一句话总结：jQuery就是普通的js对象，只不过方法比较多而已，属性就length一个。

一、jquery的链式操做的底层原理是什么？

一个方法执行完以后返回自己对象javascript

28     obj.say=function(){
29         alert('my name is :'+this.username);
30         return this;
31     }

40 // 对象链式结构
41 $('imgid').say().eat();

二、全部链式操做的原理是什么（jquery，thinkphp）？

方法执行完返回对象php

三、jquery函数体中和js函数体中地位是否同样？

彻底同样，jquery只不过是对js进行了一些轻量级的封装而已css

21 <script>
22 imgobj=document.getElementById('imgid');
23 // imgobj.onclick=function(){
24 //     this.src='b.png';
25 // }
26 
27 $(imgobj).click(function(){
28     this.src='b.png'; 
29 });
30 </script>

四、dom对象如何转成jquery对象？

在dom对象上面加上$()，$(dom)html

五、this对象和$(this)的区别？

二者都是指向当前对象，只不过this对象是dom对象，$(this)是jquery对象，区别是dom对象指行dom的方法，jquery对象执行jquery的方法java

六、jquery选择器选择出来的东西的本质是什么，好比$('h1')？

dom对象数组，而这个dom对象数组是一个jquery对象，因此jquery选择器选出来的东西均可以执行jquery的方法，而且加上下标能转化为dom对象jquery

23 val=$('h1')[1].outerHTML;

七、jquery对象（本质是dom对象列表）如何转化成dom对象？

$('h1')[1];
$('h1').get(1);linux

23 val=$('h1').get(1).outerHTML;

八、jquery的get()方法获得的是什么，好比$('h1').get()？

dom对象数组thinkphp

22 <script>
23 arr=$('h1').get();
24 alert(arr[0].outerHTML);
25 alert(arr[1].outerHTML);
26 </script>

九、jquery中的惟一属性？

length数组

十、jquery中获取jquery对象的两种方法？

size()方法和length属性框架

十一、jquery中attr()方法的实质是什么？

js中的setAttribute()和getAttribute

26 $('h1').each(function(i){ 27  $('h1').get()[i].setAttribute('num',i+1); 28 }); 29 30 $('h1').click(function(){ 31 this.innerHTML=this.getAttribute('num'); 32 });

十二、each方法做用？

由于jquery对象多为dom的数组，因此就是遍历

26 $('h1').each(function(i){ 27  $(this).attr({'num':i+1}); 28 });

1三、jquery如何获取当前元素的索引值？

index方法

76  idx=$(this).index('.menu li');

1四、jquery除什么以外的方法？

not方法

79  $('.info p').not($('.info p').eq(idx)).hide();

1五、js对象和jquery对象的区别是什么?

jquery就是js中的new Object生成的普通对象

1六、js对象和jquery对象的方法能不能共用?

不能共用

1七、js对象和jquery对象能不能互换?(能)

1.js对象->jquery对象
$(dom);

2.jquery对象->js对象
$('h1')[1];
$('h1').get(1);

1八、jquery核心方法有哪些？

size();
length;
get();
get(index);
each();
index();
data();

2、jQuery原理和核心方法

一、相关知识点

jQuery框架:
1.js对象和jquery对象的区别
2.js对象和jquery对象的转换
3.核心方法
4.选择器
5.筛选
6.属性选择器
7.文档处理
8.CSS处理
9.事件
10.效果
11.Ajax无刷新
12.工具

js对象和jquery对象的区别是什么?
jquery就是js中的new Object生成的普通对象

js对象和jquery对象的方法能不能共用?
不能共用

js对象和jquery对象能不能互换?(能)
1.js对象->jquery对象
$(dom);

2.jquery对象->js对象
$('h1')[1];
$('h1').get(1);

核心方法:
size();
length;
get();
get(index);
each();
index();
data();

二、代码

jquery对象原型开发

 1 <!doctype html>
 2 <html lang="en">
 3 <head>
 4     <meta charset="UTF-8">
 5     <title>index</title>
 6     <style>
 7  *{
 8  font-family: 微软雅黑;
 9         }
10         
11  select{
12  width:100px;
13  height:150px;
14         }
15     </style>
16     <script src="jquery.js"></script>
17 </head>
18 <body>
19     <h1>aaaaaaaaaaaaaaa</h1>
20     <h1>aaaaaaaaaaaaaaa</h1>
21     <h1>aaaaaaaaaaaaaaa</h1>
22     <h1>aaaaaaaaaaaaaaa</h1>
23 </body>
24 <script>
25 function $(attr){ 26  obj=new Object(); 27  obj.username='user123'; 28  obj.say=function(){ 29  alert('my name is :'+this.username); 30         return this; 31  } 32 
33  obj.eat=function(){ 34  alert('my am eating!'); 35  } 36 
37     return obj; 38 } 39 
40 // 对象链式结构
41 $('imgid').say().eat(); 42 </script>
43 </html>

把dom对象转成jquery对象

 1 <!doctype html>
 2 <html lang="en">
 3 <head>
 4     <meta charset="UTF-8">
 5     <title>index</title>
 6     <style>
 7  *{
 8  font-family: 微软雅黑;
 9         }
10         
11  select{
12  width:100px;
13  height:150px;
14         }
15     </style>
16     <script src="jquery.js"></script>
17 </head>
18 <body>
19     <img src="a.png" id="imgid">    
20 </body>
21 <script>
22 imgobj=document.getElementById('imgid'); 23 // imgobj.onclick=function(){
24 // this.src='b.png';
25 // }
26 
27 $(imgobj).click(function(){ 28     this.src='b.png'; 29 }); 30 </script>
31 </html>

js对象和jquery对象互换

 1 <!doctype html>
 2 <html lang="en">
 3 <head>
 4     <meta charset="UTF-8">
 5     <title>index</title>
 6     <style>
 7  *{
 8  font-family: 微软雅黑;
 9         }
10         
11  select{
12  width:100px;
13  height:150px;
14         }
15     </style>
16     <script src="jquery.js"></script>
17 </head>
18 <body>
19     <img src="a.png" id="imgid">    
20 </body>
21 <script>
22 imgobj=document.getElementById('imgid'); 23 
24 $(imgobj).click(function(){ 25     this.src='b.png'; 26     // $(this).attr({'src':'b.png'});
27 }); 28 </script>
29 </html>

jquery对象转成js对象

 1 <!doctype html>
 2 <html lang="en">
 3 <head>
 4     <meta charset="UTF-8">
 5     <title>index</title>
 6     <style>
 7  *{
 8  font-family: 微软雅黑;
 9         }
10         
11  select{
12  width:100px;
13  height:150px;
14         }
15     </style>
16     <script src="jquery.js"></script>
17 </head>
18 <body>
19     <h1>aaaaaaaaaaaaaaaaaaa</h1>
20     <h1>bbbbbbbbbbbbbbbbbbb</h1>
21 </body>
22 <script>
23 val=$('h1')[1].outerHTML; 24 alert(val); 25 </script>
26 </html>

jquery对象转成js对象2

 1 <!doctype html>
 2 <html lang="en">
 3 <head>
 4     <meta charset="UTF-8">
 5     <title>index</title>
 6     <style>
 7  *{
 8  font-family: 微软雅黑;
 9         }
10         
11  select{
12  width:100px;
13  height:150px;
14         }
15     </style>
16     <script src="jquery.js"></script>
17 </head>
18 <body>
19     <h1>aaaaaaaaaaaaaaaaaaa</h1>
20     <h1>bbbbbbbbbbbbbbbbbbb</h1>
21 </body>
22 <script>
23 val=$('h1').get(1).outerHTML; 24 alert(val); 25 </script>
26 </html>

把jquery对象转成js对象数组

 1 <!doctype html>
 2 <html lang="en">
 3 <head>
 4     <meta charset="UTF-8">
 5     <title>index</title>
 6     <style>
 7  *{
 8  font-family: 微软雅黑;
 9         }
10         
11  select{
12  width:100px;
13  height:150px;
14         }
15     </style>
16     <script src="jquery.js"></script>
17 </head>
18 <body>
19     <h1>aaaaaaaaaaaaaaaaaaa</h1>
20     <h1>bbbbbbbbbbbbbbbbbbb</h1>
21 </body>
22 <script>
23 arr=$('h1').get(); 24 alert(arr[0].outerHTML); 25 alert(arr[1].outerHTML); 26 </script>
27 </html>

size和length获取jquery对象中dom对象的个数

 1 <!doctype html>
 2 <html lang="en">
 3 <head>
 4     <meta charset="UTF-8">
 5     <title>index</title>
 6     <style>
 7  *{
 8  font-family: 微软雅黑;
 9         }
10         
11  select{
12  width:100px;
13  height:150px;
14         }
15     </style>
16     <script src="jquery.js"></script>
17 </head>
18 <body>
19     <h1>aaaaaaaaaaaaaaaaaaa</h1>
20     <h1>bbbbbbbbbbbbbbbbbbb</h1>
21 </body>
22 <script>
23 alert($('h1').size()); 24 alert($('h1').length); 25 </script>
26 </html>

单击换行号

 1 <!doctype html>
 2 <html lang="en">
 3 <head>
 4     <meta charset="UTF-8">
 5     <title>index</title>
 6     <style>
 7  *{
 8  font-family: 微软雅黑;
 9         }
10         
11  select{
12  width:100px;
13  height:150px;
14         }
15     </style>
16     <script src="jquery.js"></script>
17 </head>
18 <body>
19     <h1>aaaaaaaaaaaaaaaaaaaaaa</h1>
20     <h1>aaaaaaaaaaaaaaaaaaaaaa</h1>
21     <h1>aaaaaaaaaaaaaaaaaaaaaa</h1>
22     <h1>aaaaaaaaaaaaaaaaaaaaaa</h1>
23     <h1>aaaaaaaaaaaaaaaaaaaaaa</h1>
24 </body>
25 <script>
26 $('h1').each(function(i){ 27  $('h1').get()[i].setAttribute('num',i+1); 28 }); 29 
30 $('h1').click(function(){ 31     this.innerHTML=this.getAttribute('num'); 32 }); 33 </script>
34 </html>

each遍历jquery对象

 1 <!doctype html>
 2 <html lang="en">
 3 <head>
 4     <meta charset="UTF-8">
 5     <title>index</title>
 6     <style>
 7  *{
 8  font-family: 微软雅黑;
 9         }
10         
11  select{
12  width:100px;
13  height:150px;
14         }
15     </style>
16     <script src="jquery.js"></script>
17 </head>
18 <body>
19     <h1>aaaaaaaaaaaaaaaaaaaaaa</h1>
20     <h1>aaaaaaaaaaaaaaaaaaaaaa</h1>
21     <h1>aaaaaaaaaaaaaaaaaaaaaa</h1>
22     <h1>aaaaaaaaaaaaaaaaaaaaaa</h1>
23     <h1>aaaaaaaaaaaaaaaaaaaaaa</h1>
24 </body>
25 <script>
26 $('h1').each(function(i){ 27  $(this).attr({'num':i+1}); 28 }); 29 
30 $('h1').click(function(){ 31  $(this).html($(this).attr('num')); 32 }); 33 </script>
34 </html>

index搜索匹配的元素,并返回相应元素的索引值

 1 <!doctype html>
 2 <html lang="en">
 3 <head>
 4     <meta charset="UTF-8">
 5     <title>index</title>
 6     <style>
 7  *{
 8  font-family: 微软雅黑;
 9  margin:0px;
10  padding:0px;
11         }
12         
13  .menu{
14  height:50px;
15  background: #272822;
16  line-height: 50px;
17         }        
18 
19  .menu ul{
20  list-style:none;
21         }
22 
23  .menu ul li{
24  float: left;
25  color:#fff;
26  margin-left:15px;
27  line-height: 50px;
28  width:100px;
29  text-align:center;
30         }
31 
32  .menu ul li:hover{
33  cursor: pointer;
34  background: #ccc;    
35         }
36 
37  .info{
38  height:200px;
39  background: #ccc;
40  overflow: hidden;
41  padding:15px;
42         }
43 
44  .info p{
45  display: none;
46         }
47 
48  .info p:first-child{
49  display: block;
50         }
51 
52  .menu a:hover{
53  background: #ccc;
54         }
55     </style>
56     <script src="jquery.js"></script>
57 </head>
58 <body>
59     <div class='menu'>
60         <ul>
61             <li>linux</li>
62             <li>php</li>
63             <li>javascript</li>
64         </ul>    
65     </div>
66 
67     <div class='info'>
68         <p>linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!</p>    
69 
70         <p>php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!</p>    
71         <p>javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!</p>    
72     </div>
73 </body>
74 <script>
75 $('.menu li').mouseenter(function(){ 76  idx=$(this).index('.menu li'); 77 
78  $('.info p').eq(idx).show(); 79  $('.info p').not($('.info p').eq(idx)).hide(); 80 }); 81 </script>
82 </html>

酒仙网上标签页效果

 1 <!doctype html>
 2 <html lang="en">
 3 <head>
 4     <meta charset="UTF-8">
 5     <title>index</title>
 6     <style>
 7  *{
 8  font-family: 微软雅黑;
 9  margin:0px;
10  padding:0px;
11         }
12         
13  .menu{
14  height:50px;
15  background: #272822;
16  line-height: 50px;
17         }        
18 
19  .menu ul{
20  list-style:none;
21         }
22 
23  .menu ul li{
24  float: left;
25  color:#fff;
26  margin-left:15px;
27  line-height: 50px;
28  width:100px;
29  text-align:center;
30         }
31 
32  .menu ul li:hover{
33  cursor: pointer;
34  background: #ccc;    
35         }
36 
37  .info{
38  height:200px;
39  background: #ccc;
40  overflow: hidden;
41  padding:15px;
42         }
43 
44  .info p{
45  display: none;
46         }
47 
48  .info p:first-child{
49  display: block;
50         }
51 
52  .menu a:hover{
53  background: #ccc;
54         }
55     </style>
56     <script src="jquery.js"></script>
57 </head>
58 <body>
59     <div class='menu'>
60         <ul>
61             <li>linux</li>
62             <li>php</li>
63             <li>javascript</li>
64         </ul>    
65     </div>
66 
67     <div class='info'>
68         <p>linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!linux is very much!</p>    
69 
70         <p>php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!php is very much!</p>    
71         <p>javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!javascript is very much!</p>    
72     </div>
73 </body>
74 <script>
75 $('.menu li').eq(0).css({'background':'#ccc'}); 76 
77 $('.menu li').mouseenter(function(){ 78  $(this).css({'background':'#ccc'}); 79  $('.menu li').not($(this)).css({'background':'#272822'}); 80 
81 
82  idx=$(this).index('.menu li'); 83 
84  $('.info p').eq(idx).show(); 85  $('.info p').not($('.info p').eq(idx)).hide(); 86 }); 87 </script>
88 </html>

data往jquery对象身上赋值

 1 <!doctype html>
 2 <html lang="en">
 3 <head>
 4     <meta charset="UTF-8">
 5     <title>index</title>
 6     <style>
 7  *{
 8  font-family: 微软雅黑;
 9         }
10         
11  select{
12  width:100px;
13  height:150px;
14         }
15     </style>
16     <script src="jquery.js"></script>
17 </head>
18 <body>
19     <h1>aaaaaaaaaaaaaaaaaaaaaa</h1>
20     <h1>aaaaaaaaaaaaaaaaaaaaaa</h1>
21     <h1>aaaaaaaaaaaaaaaaaaaaaa</h1>
22     <h1>aaaaaaaaaaaaaaaaaaaaaa</h1>
23     <h1>aaaaaaaaaaaaaaaaaaaaaa</h1>
24 </body>
25 <script>
26 $('h1').each(function(i){ 27  $(this).data({'num':i+1}); 28 }); 29 
30 $('h1').click(function(){ 31  $(this).html($(this).data('num')); 32 }); 33 </script>
34 </html>