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JQuery learning summary

高洛峰
高洛峰Original
2016-12-03 09:50:311099browse

JQuery learning summary [1]

1: JQuery

1 JQuery knowledge

*: Let us learn to call the JQ plug-in, which is actually an encapsulation of JS internally.

*: There are three files in jquery.

JQuery learning summary

The second and third files actually have the same content, but the third one has been compressed to shorten the browser's access time. .

We put Jquery-1.4.2.js and jquery.1.4.2-vsdoc and js together when using them. In fact, vsdoc.js is the explanation for the previous explanation. It allows us to write code. Click to operate.

*: Practice "Click the button to pop up the content of the dialog box" "Click the text in the web page to make the text disappear line by line" ("$" is actually a function)

<head> 
<script type="text/javascript" src="js/jquery-1.4.2.js"></script> 
<script type="text/javascript"> 
 $(function() { 
 
 $("#btn").click(function () { alert($("#un").val()); });//点击弹出内容 
 
 $("div").click(function() { $(this).hide("slow"); });//文字消失 
 
 }); 
</script> 
</head> 
<body> 
<input type="text"id="un"/> 
<input type="button" id="btn"/> 
<div>文字内容</div> 
</body>

2 Ready in JQuery "Pop up at the beginning of the web page" Content》

$(dounction).ready(function(){alert("Loading completed");})

In fact, you can also write it like this

$(function(){alert("Loading completed");} );

3 jquery built-in function

.map(array,fn) calls the fn function to process each element in the array. The fn function will process and return, and finally get a new array. .map(array,fn) calls the fn function to process each element in the array. The fn function returns the processing and finally gets a new array. map cannot handle Dictionary-style arrays. Use the following $.each to process.

$.each(array.fn) calls the fn function to process each element of the array arr, with no return value. 

var arr=[3,5,7]; 
Var arr2=$map.(arr,function(item){return item*2}) 函数式编程。 
Var arr={“tom”;”檀木”,”xiaozhang”;”小张”} 
$.each(arr,function(key,value){alert(key+”=”+value);});

4 JQuery object, Dom object

The Jquery object is generated by wrapping the Dom object through jquery. And jquery objects can only call methods encapsulated by jquery objects. Methods of Dom objects cannot be called.

$(function(){$("#id").css("background","red")});

The above code is copied, which is to set the background color to red. If in .css If the attribute is one, the value is obtained, and if there are two attributes, the value is set.

5 jquery selector

*id selector

$("#div").html();

*TabName selector

$("div").click( function()｛alert("Hello, I am p");｝);

Here is to select all the div tags in the web page and add click events to them.

* css selector

Selecting multiple styles at the same time is to add customized styles.

$(“div”).click(function(){alert(“This is information”)});

6 Multi-condition selector/hierarchical selector

JQuery learning summary

7 jquery iteration

That’s it The error program will not give an error prompt. We need to add if/elae statements to make judgments.

JQuery learning summary

8 jquery’s node traversal

uses the next() and nextall() methods to traverse. It's the same as traversing the array. Here we just get the value of its next element.

Siblings(): Get the sibling elements (sibling nodes) of all elements.

*: jquery’s chain programming

$("div").click(function(){
$(this).css("background","red").siblings("div").css("background","white")
});

is easy to operate through the dot operator.

//This is a chain operation, which reduces the use of if/else and other operations. Changed programming style. 

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
 <meta charset="utf-8" />
 <title></title>
 <script src="js/jquery-1.4.2-vsdoc.js"></script>
 <script src="js/jquery-1.4.2.js"></script>
 <script type="text/javascript">
 $(function() {
 $("#tables td").html("<img  src=&#39;images/1.jpg&#39;/ alt="JQuery learning summary" >")
 .mouseover(function () {
 $("#tables td") .html("<img  src=&#39;images/1.jpg&#39;/ alt="JQuery learning summary" >");
 $(this).nextAll().html("<img src=&#39;images/2.jpg&#39;/");
 });
 });
 </script>
</head>
<body>
 <table id="tables">
 <tr><td></td><td></td><td></td><td></td></tr>
 </table>
</body>
</html>

9: Basic filters

JQuery learning summary

You can write them together here, such as selectors and filters, which will be very powerful.

You can not only use the selector for absolute positioning, but also for relative positioning. Just specify the second parameter in $(), and the second parameter is a relative element.

Case:

JQuery learning summary

(relative positioning)

JQuery learning summary

: The element here is the positioning of td under positioning #tables tr

10 attribute filter

JQuery learning summary

Eg: 

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
 <meta charset="utf-8" />
 <script src="js/jquery-1.4.2.js"></script>
 <script src="js/jquery-1.4.2-vsdoc.js"></script>
 <title></title>
 <script type="text/javascript">
 $(function() {
 $("input[value=显示选中的内容]").click(function() {
 alert($("input:checked").val());
 });
 });
 </script>
</head>
<body>
 <input type="checkbox" value="上海"/>上海<br/>
 <input type="checkbox" value="宝鸡"/>宝鸡<br/>
 <input type="checkbox" value="深圳"/>深圳<br/>
 <input type="checkbox" value="西安"/>西安<br/>
 <input type="checkbox" value="北京"/>北京<br/>
 <input type="submit" value="显示选中的内容"/>
</body>
</html>

11 Each element of each 

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
 <meta charset="utf-8" />
 <script src="js/jquery-1.4.2.js"></script>
 <script src="js/jquery-1.4.2-vsdoc.js"></script>
 <title></title>
 <script type="text/javascript">
 $(function() {
 $("input[name=names]").click(function() {
 var arr = new Array();
 $("input[name=names]:checked").each(function (key, value) {
 arr[key] = $(value).val();
 });
 $("#msgNames").text("共选中"+arr.length+"项:"+arr.join(","));
 });
 });
 </script>
</head>
<body>
 <input type="checkbox" name="names" value="张辉"/>张辉
 <input type="checkbox" name="names" value="妈妈"/>妈妈
 <input type="checkbox" name="names" value="妈妈"/>妈妈
 <input type="checkbox" name="names" value="妈妈"/>妈妈
 <p id="msgNames"></p>
</body>

JQuery learning summary

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