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A collection of jquery methods for traversing and filtering arrays and json objects

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Apr 24, 2018 pm 02:36 PM

javascript jquery json

This time I bring you a collection of methods for jquery to traverse and filter arrays and json objects. What are the precautions for jquery to traverse and filter arrays and json objects? The following is a practical case, let's take a look.

jquery grep() filter

Traverse the array

$().ready( 
function(){ 
var array = [1,2,3,4,5,6,7,8,9]; 
var filterarray = $.grep(array,function(value){ 
return value > 5;//筛选出大于5的 
}); 
for(var i=0;i<filterarray.length;i++){ 
alert(filterarray[i]); 
} 
for (key in filterarray){ 
alert(filterarray[key]); 
} 
} 
);

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jquery each() filter the traverse array

$().ready( 
function(){ 
var anObject = {one:1,two:2,three:3};//对json数组each 
$.each(anObject,function(name,value) { 
alert(name); 
alert(value); 
}); 
var anArray = [&#39;one&#39;,&#39;two&#39;,&#39;three&#39;]; 
$.each(anArray,function(n,value){ 
alert(n); 
alert(value); 
} 
); 
} 
);

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jquery inArray() filter the traverse array

$().ready( 
function(){ 
var anArray = [&#39;one&#39;,&#39;two&#39;,&#39;three&#39;]; 
var index = $.inArray(‘two&#39;,anArray); 
alert(index);//返回该值在数组中的键值，返回1 
alert(anArray[index]);//value is two 
} 
);

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jquery map() filters and traverses the array

$().ready( 
function(){ 
var strings = [&#39;0&#39;,&#39;1&#39;,&#39;2&#39;,&#39;3&#39;,&#39;4&#39;,&#39;S&#39;,&#39;6&#39;]; 
var values = $.map(strings,function(value){ 
var result = new Number(value); 
return isNaN(result) ? null:result;//isNaN:is Not a Number的缩写 
} 
); 
for (key in values) { 
alert(values[key]); 
} 
} 
);

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js traverses and parses json object 1

var json = [{dd:&#39;SB&#39;,AA:&#39;东东&#39;,re1:123},{cccc:&#39;dd&#39;,lk:&#39;1qw&#39;}]; 
for(var i=0,l=json.length;i<l;i++){ 
for(var key in json[i]){ 
alert(key+&#39;:&#39;+json[i][key]); 
} 
}

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js traverses and parses json object 2

There are the following json objects:

1 2	`var` `obj ={”name”:”冯娟”,”password”:”123456″,”department”:”技术部”,”sex”:” 女”,”old”:30}; 遍历方法：` `for(var` `p in obj){ str = str+obj[p]+',';` `return` `str; }`

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The following is an example to illustrate the specific implementation method

How JQuery gets the object

$(‘#id&#39;) ：通过元素的id 
$(‘tagName&#39;) : 通过元素的标签名 
$(‘tagName tagName&#39;) : 通过元素的标签名,eg: $(‘ul li&#39;) 
$(‘tagName#id): 通过元素的id和标签名 
$(‘:checkbox&#39;):拿取input的 type为checkbox&#39;的所有元素: 
Eg: <input type="checkbox" name="appetizers"
value="imperial"/> 
$('span[price] input[type=text]') ：拿取下面的input元素 
<span price="3"> 
<input type="text" name="imperial.quantity"
disabled="disabled" value="1"/> 
</span> 
$('p',$(this).parents('p:first'))：拿取该p的上（至少都是父节点）的第一个p节点 
$('~ span:first',this)： locates the first sibling of this that's a <span> element.

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Lazy loading of js files:

$.getScript
Example:
Html file:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> 
<html> 
<head> 
<title>$.getScript Example</title> 
<link rel="stylesheet" type="text/css" href="../common.css"> 
<script type="text/javascript"
src="../scripts/jquery-1.2.1.js"></script> 
<script type="text/javascript"> 
$(function(){ 
$('#loadButton').click(function(){ 
$.getScript(//在Firefox/3.0.1中会出现一个错误(语法错误,定义的变量不起作用,ff2没问题) 
'new.stuff.js'//,function(){$('#inspectButton').click()} 
); 
}); 
$('#inspectButton').click(function(){ 
someFunction(someVariable); 
test() 
}); 
}); 
</script> 
</head> 
<body> 
<button type="button" id="loadButton">Load</button> 
<button type="button" id="inspectButton">Inspect</button> 
</body> 
</html> 
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> 
<html> 
<head> 
<title>$.getScript Example</title> 
<link rel="stylesheet" type="text/css" href="../common.css"> 
<script type="text/javascript"
src="../scripts/jquery-1.2.1.js"></script> 
<script type="text/javascript"> 
$(function(){ 
$('#loadButton').click(function(){ 
$.getScript(//在Firefox/3.0.1中会出现一个错误(语法错误,定义的变量不起作用,ff2没问题) 
'new.stuff.js'//,function(){$('#inspectButton').click()} 
); 
}); 
$('#inspectButton').click(function(){ 
someFunction(someVariable); 
test() 
}); 
}); 
</script> 
</head> 
<body> 
<button type="button" id="loadButton">Load</button> 
<button type="button" id="inspectButton">Inspect</button> 
</body> 
</html>

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Js file:

alert("I'm inline!"); 
var someVariable = 'Value of someVariable'; 
function someFunction(value) { 
alert(value); 
} 
function test() { 
alert('test'); 
} 
alert("I'm inline!"); 
var someVariable = 'Value of someVariable'; 
function someFunction(value) { 
alert(value); 
} 
function test() { 
alert('test'); 
}

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jquery array processing:

100

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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> 
<html> 
<head> 
<title>Hi!</title> 
<script type="text/javascript" src="../scripts/jquery-1.2.1.js"> 
</script> 
<script type="text/javascript"> 
var $ = 'Hi!'; 
jQuery(function(){ 
alert('$ = '+ $);//这里的 $ 为 Hi!,把它变回jquery的符号:jQuery(function($){...}/这样就可以了 
//alert(jQuery) 
}); 
jQuery(function($){ 
//------------遍历数组 .each的使用------------- 
var anArray = ['one','two','three']; 
$.each(anArray,function(n,value) { 
//do something here 
//alert(n+' '+value); 
}); 
var anObject = {one:1, two:2, three:3}; 
$.each(anObject,function(name,value) { 
//do something here 
//alert(name+' '+value); 
}); 
//-----------过滤数组 .grep的使用------------ 
var originalArray =[99,101,103]; 
var bigNumbers = $.grep(originalArray,'a>100');//第2种写法,还可以用正则表达式来过滤 
$.each(bigNumbers,function(n,value) { 
//do something here 
//alert(n+' '+value); 
}); 
//------------转换数组 .map的使用------------ 
var strings = ['1','2','3','4','S','K','6']; 
var values = $.map(strings,function(value){ 
var result = new Number(value); 
return isNaN(result) ? null : result;//如果result不是数字则 返回null（返回null在这里相当于不返回） 
}); 
$.each(values,function(n,value) { 
//do something here 
//alert(value); 
}); 
var characters = $.map( 
['this','that','other thing'], 
function(value){return value.split('');}//分离字符串用返回给characters 
); 
//alert(characters.length); 
//------------.inArray(value,array)的使用------------返回value在array下标的位置，如果value不在array中则返回-1 
var index = $.inArray(2,[1,2,3,4,5]); 
//alert(index); 
//------------makeArray(obj)的使用------------将类数组对象转换为数组对象。 
var arr = jQuery.makeArray(document.getElementsByTagName_r("p")); 
//arr.reverse(); // 使用数组翻转函数 
$.each(arr,function(n,value) { 
//do something here 
//alert(n+' '+value); 
//alert(value.html()); 
}); 
var arr2 =$.unique(document.getElementsByTagName_r("p")); //获得唯一的对象，看API,说得很模 
糊,http://docs.jquery.com/Utilities/jQuery.unique 
alert(); 
$.each(arr2,function(n,value) { 
//do something here 
alert(n+' '+value); 
}); 
}); 
</script> 
</head> 
<body> 
<p>First</p><p>Second</p><p>Third</p><p>Fourth</p><p>Fourth</p> 
</body> 
</html> 
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> 
<html> 
<head> 
<title>Hi!</title> 
<script type="text/javascript" src="../scripts/jquery-1.2.1.js"> 
</script> 
<script type="text/javascript"> 
var $ = 'Hi!'; 
jQuery(function(){ 
alert('$ = '+ $);//这里的 $ 为 Hi!,把它变回jquery的符号:jQuery(function($){...}/这样就可以了 
//alert(jQuery) 
}); 
jQuery(function($){ 
//------------遍历数组 .each的使用------------- 
var anArray = ['one','two','three']; 
$.each(anArray,function(n,value) { 
//do something here 
//alert(n+' '+value); 
}); 
var anObject = {one:1, two:2, three:3}; 
$.each(anObject,function(name,value) { 
//do something here 
//alert(name+' '+value); 
}); 
//-----------过滤数组 .grep的使用------------ 
var originalArray =[99,101,103]; 
var bigNumbers = $.grep(originalArray,'a>100');//第2种写法,还可以用正则表达式来过滤 
$.each(bigNumbers,function(n,value) { 
//do something here 
//alert(n+' '+value); 
}); 
//------------转换数组 .map的使用------------ 
var strings = ['1','2','3','4','S','K','6']; 
var values = $.map(strings,function(value){ 
var result = new Number(value); 
return isNaN(result) ? null : result;//如果result不是数字则 返回null（返回null在这里相当于不返回） 
}); 
$.each(values,function(n,value) { 
//do something here 
//alert(value); 
}); 
var characters = $.map( 
['this','that','other thing'], 
function(value){return value.split('');}//分离字符串用返回给characters 
); 
//alert(characters.length); 
//------------.inArray(value,array)的使用------------返回value在array下标的位置，如果value不在array中则返回 
-1 
var index = $.inArray(2,[1,2,3,4,5]); 
//alert(index); 
//------------makeArray(obj)的使用------------将类数组对象转换为数组对象。 
var arr = jQuery.makeArray(document.getElementsByTagName_r("p")); 
//arr.reverse(); // 使用数组翻转函数 
$.each(arr,function(n,value) { 
//do something here 
//alert(n+' '+value); 
//alert(value.html()); 
}); 
var arr2 =$.unique(document.getElementsByTagName_r("p")); //获得唯一的对象，看API,说得很模 
糊,http://docs.jquery.com/Utilities/jQuery.unique 
alert(); 
$.each(arr2,function(n,value) { 
//do something here 
alert(n+' '+value); 
}); 
}); 
</script> 
</head> 
<body> 
<p>First</p><p>Second</p><p>Third</p><p>Fourth</p><p>Fourth</p> 
</body> 
</html>

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I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to other related articles on the PHP Chinese website!

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A collection of jquery methods for traversing and filtering arrays and json objects

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