<label for='my_file' class="theme-color">
 <mu-icon left value="backup"></mu-icon>
 修改头像
</label>
<input type="file" ref="upload" name="avatar" id='my_file' style="display:none;" accept="image/jpg" @change="changeAvatar" />

let ChangeAvatar = (img) => axios({
 url: '/user/changeavatar',
 method: 'post',
 anync: true,
 contentType: false,
 processData: false,
 data: img
})

 methods: {
  changeAvatar (event) {
   let img = event.target.files[0];
   let size = img.size;
   if (size > 3145728) {
    alert('请选择3M以内的图片！');
    return false;
   }
   let Form = new FormData();
   Form.append('avatar', img, this.avatar_name);
   API.ChangeAvatar(Form)
    .then((response) => {
     console.log(response)
    })
    .catch((error) => {
     console.log(error)
    })
  }
 }

const fileUpload = require('express-fileupload');
app.use(fileUpload());

app.post('/user/changeavatar', function(req, res) {
 console.log(req.files); // the uploaded file object
 let avatar = req.files.avatar;

 // Use the mv() method to place the file somewhere on your server
 avatar.mv('dist/static/img/avatar/'+req.files.avatar.name+'.jpg', function(err) {
  if (err)
   return res.status(500).send(err);

  res.send('File uploaded!');
 });
})