从jQuery 1.5开始，所有jQuery的Ajax方法都返回一个jqXHR对象，提供.error()、.success()和.complete()个方法.
.success()和.complete()之间有什么区别？
从jQuery 1.5开始，所有jQuery的Ajax方法都返回一个jqXHR对象，提供.error()、.success()和.complete()个方法.
.success()和.complete()之间有什么区别？
.success() only gets called if your webserver responds with a 200 OK HTTP header - basically when everything is fine.
However, .complete() will always get called no matter if the ajax call was successful or not - maybe it outputted errors and returned an error - .complete() will still get called.
值得一提的是，.complete()会被称为after,.success()会被称为.success()-如果这对你很重要.