问使用jQuery的文件上载进度条

EN

$.ajax({
  xhr: function() {
    var xhr = new window.XMLHttpRequest();

    xhr.upload.addEventListener("progress", function(evt) {
      if (evt.lengthComputable) {
        var percentComplete = evt.loaded / evt.total;
        percentComplete = parseInt(percentComplete * 100);
        console.log(percentComplete);

        if (percentComplete === 100) {

        }

      }
    }, false);

    return xhr;
  },
  url: posturlfile,
  type: "POST",
  data: JSON.stringify(fileuploaddata),
  contentType: "application/json",
  dataType: "json",
  success: function(result) {
    console.log(result);
  }
});

ajax = new XMLHttpRequest();
ajax.onreadystatechange = function () {

    if (ajax.status) {

        if (ajax.status == 200 && (ajax.readyState == 4)){
            //To do tasks if any, when upload is completed
        }
    }
}
ajax.upload.addEventListener("progress", function (event) {

    var percent = (event.loaded / event.total) * 100;
    //**percent** variable can be used for modifying the length of your progress bar.
    console.log(percent);

});

ajax.open("POST", 'your file upload link', true);
ajax.send(formData);
//ajax.send is for uploading form data.