jQuery的serialize模块中有个r20正则
复制代码 代码如下:
var r20 = /%20/g,

jQuery.param方法中会将所有的"%20"转成"+"，即提交数据前，数据中如果包含空格，那经过encodeURIComponent后，空格会转成"%20"
复制代码 代码如下:
encodeURIComponent(' ') === '%20'; // true

最后需要将"%20"转换成"="再Post提交。这样后台程序接受到的才是真正的空格。

关于 encodeURIComponent，见MDC描述

encodeURIComponent escapes all characters except the following: alphabetic, decimal digits, - _ . ! ~ * ' ( )

To avoid unexpected requests to the server, you should call encodeURIComponent on any user-entered parameters that will be passed as part of a URI. For example, a user could type "Thyme &time=again" for a variable comment. Not using encodeURIComponent on this variable will give comment=Thyme%20&time=again. Note that the ampersand and the equal sign mark a new key and value pair. So instead of having a POST comment key equal to "Thyme &time=again", you have two POST keys, one equal to "Thyme " and another (time) equal to again.

For application/x-ponent
http://www.w3.org/TR/html401/interact/forms.html#form-content-type