如果用户对表单应用了任何更改，则在他们离开当前页面时提示用户
用法
使所有表单都跟踪“脏状态”
$ ( "form" ) //select either a form or directly select input elements in a form to only track individual fields of a form
. dirtyForm ( )
. submit ( function ( ) {
$ ( this ) . markClean ( ) ; //when submitting a form we need to mark it as clean so that the form can post away from the current page
} ) ;
禁用单个元素的“脏”检查（取消按
