Xhr uploading event.loaded issue

问题

opts.xhr=function(){
    var xhr = new window.XMLHttpRequest();

    // Upload progress
    xhr.upload.onprogress = function(e) {
        if (e.lengthComputable) {
            var percentComplete = e.loaded / e.total * 100;
            console.log('Progress info:', e.loaded, e.total, Math.round(percentComplete),  Math.round(e.loaded/1024/1024), Math.round(e.total/1024/1024));
        }
    }
    return xhr;
}
return $.ajax(opts);

Progress info: 53657600 2666153229 2 51 2543

Progress info: 55656448 2666153229 2 53 2543

Progress info: 57655296 2666153229 2 55 2543

Progress info: 59850752 2666153229 2 57 2543

Progress info: 4489216 2666153229 0 4 2543

Progress info: 4800512 2666153229 0 5 2543

WTF?!

Why it's jumping back? Shows 59850752 is loaded and then 4489216. O_o What i'm doing wrong?

Request URL:http://mydomain.com/admin/upload?callback=jQuery18307878572104964405_1372440424301

Request Headers

Accept:text/javascript, application/javascript, application/ecmascript, application/x-ecmascript, */*; q=0.01
Content-Type:multipart/form-data; boundary=----WebKitFormBoundaryVHTBFWPenOcByyrT
Origin:http://mydomain.com
Referer:http://mydomain.com/admin/add
User-Agent:Mozilla/5.0 (Windows NT 6.2; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/27.0.1453.116 Safari/537.36
X-Requested-With:XMLHttpRequest

Query String Parameters

callback:jQuery18307878572104964405_1372440424301

Request Payload

------WebKitFormBoundaryVHTBFWPenOcByyrT
Content-Disposition: form-data; name="images[]"; filename="smerch_BDRip-AVC.mkv"
Content-Type: application/octet-stream


------WebKitFormBoundaryVHTBFWPenOcByyrT--

来源：https://stackoverflow.com/questions/17370382/xhr-uploading-event-loaded-issue

标签

javascript

ajax

upload