Jquery 简明教程

jQuery - Utilities

Jquery 提供了一些 $(name space) 格式的实用程序。这些方法有助于完成编程任务。下面展示其中几个实用程序方法。

Jquery provides serveral utilities in the formate of $(name space). These methods are helpful to complete the programming tasks.a few of the utility methods are as show below.

$.trim()

$.trim() 用于移除前导和尾随空白

$.trim() is used to Removes leading and trailing whitespace

$.trim( "    lots of extra whitespace    " );

$.each()

$.each() 用于迭代数组和对象

$.each() is used to Iterates over arrays and objects

$.each([ "foo", "bar", "baz" ], function( idx, val ) {
   console.log( "element " + idx + " is " + val );
});

$.each({ foo: "bar", baz: "bim" }, function( k, v ) {
   console.log( k + " : " + v );
});

$.inArray()

each() can be called on a selection to iterate over the elements contained in the selection. .each(), not $.each(), should be used for iterating over elements in a selection.

$.inArray() 用于返回某个值在数组中的索引，如果数组中不存在该值，则返回 -1。

each() can be called on a selection to iterate over the elements contained in the selection. .each(), not $.each(), should be used for iterating over elements in a selection.

$.inArray() is used to Returns a value’s index in an array, or -1 if the value is not in the array.

var myArray = [ 1, 2, 3, 5 ];

if ( $.inArray( 4, myArray ) !== -1 ) {
   console.log( "found it!" );
}

$.extend()

$.extend() 用于使用后续对象的属性更改第一个对象的属性。

$.extend() is used to Changes the properties of the first object using the properties of subsequent objects.

var firstObject = { foo: "bar", a: "b" };
var secondObject = { foo: "baz" };

var newObject = $.extend( firstObject, secondObject );

console.log( firstObject.foo );
console.log( newObject.foo );

$.proxy()

$.proxy() 用于返回一个总是在给定范围中运行的函数——即，将传入函数中的 this 的含义设置为第二个参数

$.proxy() is used to Returns a function that will always run in the provided scope — that is, sets the meaning of this inside the passed function to the second argument

var myFunction = function() {
   console.log( this );
};

var myObject = {
   foo: "bar"
};

myFunction(); // window

var myProxyFunction = $.proxy( myFunction, myObject );

myProxyFunction();

$.browser

$.browser 用于提供浏览器信息

$.browser is used to give the information about browsers

jQuery.each( jQuery.browser, function( i, val ) {
   $( "<div>" + i + " : <span>" + val + "</span>" )
   .appendTo( document.body );
});

$.contains()

$.contains() 用于判断由第二个参数提供的 DOM 元素是否是直接后代还是更深层嵌套后代的第一个参数提供的 DOM 元素的子级，返回 true。

$.contains() is used to returns true if the DOM element provided by the second argument is a descendant of the DOM element provided by the first argument, whether it is a direct child or nested more deeply.

$.contains( document.documentElement, document.body );
$.contains( document.body, document.documentElement );

$.data()

$.data() 用于提供数据信息

$.data() is used to give the information about data

<html lang = "en">
   <head>
      <title>jQuery.data demo</title>
      <script src = "https://code.jquery.com/jquery-1.10.2.js">
      </script>
   </head>

   <body>
      <div>
         The values stored were <span></span>
            and <span></span>
      </div>

      <script>
         var div = $( "div" )[ 0 ];

         jQuery.data( div, "test", {
            first: 25,
            last: "tutorials"
         });

         $( "span:first" ).text( jQuery.data( div, "test" ).first );
         $( "span:last" ).text( jQuery.data( div, "test" ).last );
      </script>
   </body>
</html>

输出如下

An output would be as follows

The values stored were 25 and tutorials

$.fn.extend()

$.fn.extend() 用于扩展 jQuery 原型

$.fn.extend() is used to extends the jQuery prototype

<html lang = "en">
   <head>
      <script src = "https://code.jquery.com/jquery-1.10.2.js">
      </script>
   </head>

   <body>
      <label><input type = "checkbox" name = "android">
         Android</label>
      <label><input type = "checkbox" name = "ios"> IOS</label>

      <script>
         jQuery.fn.extend({

            check: function() {
               return this.each(function() {
                  this.checked = true;
               });
            },
            uncheck: function() {
               return this.each(function() {
                  this.checked = false;
               });
            }
         });

         // Use the newly created .check() method
         $( "input[type = 'checkbox']" ).check();

      </script>
   </body>
</html>

它提供以下所示的输出 −

It provides the output as shown below −

$.isWindow()

$.isWindow() 用于识别窗口

$.isWindow() is used to recognise the window

<!doctype html>
<html lang = "en">
   <head>
      <meta charset = "utf-8">
      <title>jQuery.isWindow demo</title>
      <script src = "https://code.jquery.com/jquery-1.10.2.js">
      </script>
   </head>

   <body>
      Is 'window' a window? <b></b>

      <script>
         $( "b" ).append( "" + $.isWindow( window ) );
      </script>
   </body>
</html>

它提供以下所示的输出 −

It provides the output as shown below −

$.now()

它返回一个代表当前时间数字

It returns a number which is representing the current time

(new Date).getTime()

$.isXMLDoc()

$.isXMLDoc() 检查文件是否是 xml

$.isXMLDoc() checks whether a file is an xml or not

jQuery.isXMLDoc( document )
jQuery.isXMLDoc( document.body )

$.globalEval()

$.globalEval() 用于全局执行 javascript

$.globalEval() is used to execute the javascript globally

function test() {
   jQuery.globalEval( "var newVar = true;" )
}
test();

$.dequeue()

$.dequeue() 用于执行队列中的下一个函数

$.dequeue() is used to execute the next function in the queue

<!doctype html>
<html lang = "en">
   <head>
      <meta charset = "utf-8">
      <title>jQuery.dequeue demo</title>

      <style>
         div {
            margin: 3px;
            width: 50px;
            position: absolute;
            height: 50px;
            left: 10px;
            top: 30px;
            background-color: green;
            border-radius: 50px;
         }
         div.red {
            background-color: blue;
         }
      </style>

      <script src = "https://code.jquery.com/jquery-1.10.2.js"></script>
   </head>

   <body>
      <button>Start</button>
      <div></div>

      <script>
         $( "button" ).click(function() {
            $( "div" )
            .animate({ left: '+ = 400px' }, 2000 )
            .animate({ top: '0px' }, 600 )

            .queue(function() {
               $( this ).toggleClass( "red" );
               $.dequeue( this );
            })

            .animate({ left:'10px', top:'30px' }, 700 );
         });
      </script>
   </body>
</html>

它提供以下所示的输出 −

It provides the output as shown below −