axios 上传显示进度

使用 onUploadProgress 实现

let self = this
this.axios.put(this.uploadUrl, this.files[0], {
  headers: {
    'Content-Type': 'multipart/form-data'
  },
  transformRequest: [function (data) {
    return data
  }],
  onUploadProgress: progressEvent => {
    let complete = (progressEvent.loaded / progressEvent.total * 100 | 0) + '%'
    self.uploadMessage = '上传 ' + complete
  }
})
.then((response) => {
  if (response.status === 200) {
    self.uploadMessage = '上传成功！'
  }
})