.ajaxComplete( handler )
用来注册一个ajax请求结束时执行的函数。
handler格式：
Function( Event event, jqXHR jqXHR, PlainObject ajaxOptions )
$( document ).ajaxComplete(function( event, xhr, settings ) {
if ( settings.url === "ajax/test.html" ) {
$( ".log" ).text( "Triggered ajaxComplete handler. The result is " + xhr.responseText );
}
});
