This is why you have to specify jQuery. Notice the following about the HTML form above: The enctype attribute of the. 涉及到两个对象FormData和XMLHttpRequest. BeginForm(). File uploads are not performed using normal "Ajax" techniques, that is they are not performed using XMLHttpRequests. Related: AngularJS Multiple File Upload using XMLHttpRequest and Web API. nginx_uploadprogress_module - an implementation of an upload progress system, that monitors RFC1867 POST upload as they are transmitted to upstream servers. 5 was released in July 2000, but was not fully discovered until AJAX and Web 2. If this method is called several times with the same header, the values are merged into one single request header. This method of using a header would typically be used in conjunction with XMLHttpRequest on implementations that do not