Jquery1.6版本后attr的变化

原文链接：http://www.cnblogs.com/-run/archive/2011/11/16/2251569.html

Jquery1.6版本后attr的变化

Jquery1.6版本后 attr 改动后的效果：
jquery1.6+版本：

下文来自www.jquery.com The difference betweenattributes and properties can be important in specific situations.Before jQuery 1.6, the .attr() method sometimes took property values into account when retrieving some attributes, which could cause inconsistent behavior.As of jQuery 1.6, the .prop() method provides a way to explicitly retrieve property values, while.attr() retrieves attributes For example, selectedIndex,tagName, nodeName, nodeType, ownerDocument,defaultChecked, and defaultSelected should be retrieved and set with the.prop() method. Prior to jQuery 1.6, these properties were retrievable with the.attr() method, but this was not within the scope of attr. These do not have corresponding attributes and are only properties.

`elem.checked`	`true` (Boolean) Will change with checkbox state
`$(elem).prop("checked")`	`true` (Boolean) Will change with checkbox state
`elem.getAttribute("checked")`	`"checked"` (String) Initial state of the checkbox; does not change
`$(elem).attr("checked")`(1.6)	`"checked"` (String) Initial state of the checkbox; does not change
`$(elem).attr("checked")`(1.6.1+)	`"checked"` (String) Will change with checkbox state
`$(elem).attr("checked")`(pre-1.6)	`true` (Boolean) Changed with checkbox state

//勾选后输出：
//attr('checked'): checked
//.prop('checked'): true
//.is(':checked'): true//取消勾选输出：//.attr('checked'): undefined
//.prop('checked'): false
//.is(':checked'): false

jquery1.4 版本：

 1 <!DOCTYPE html> 
 2 <html> 
 3 <head> 
 4 <style> 
 5 p { margin: 20px 0 0 } 
 6 b { color: blue; } 
 7 </style> 
 8 <script src="../js/jquery-1.4.4.js"></script> 
 9 </head> 
10 <body> 
11    
12 <input id="check1" type="checkbox" checked="checked"> 
13 <label for="check1">Check me</label> 
14 <p></p> 
15  
16 <script> 
17 $("input").change(function() { 
18   var $input = $(this); 
19   $("p").html(".attr('checked'): <b>" + $input.attr('checked') + "</b><br>" 
20               + ".is(':checked'): <b>" + $input.is(':checked') ) + "</b>"; 
21 }).change(); 
22 </script> 
23  
24 </body> 
25 </html>

勾选后输出：
//attr('checked'): true
//.prop('checked')  1.6后版本才有这个方法
//.is(':checked'): true
取消勾选输出：//.attr('checked'): false
//.prop('checked')1.6后版本才有这个方法
//.is(':checked'): false