vue上传文件显示进度条

var form = new FormData()
    form.append('file', vm.$refs.upload.files[0])

    form.append('id', id)

    form.append('type', type)

    var config = {

        onUploadProgress: progressEvent => {

            var complete = (progressEvent.loaded / progressEvent.total * 100 | 0) + '%'

            this.progress = complete

        }

    }

    axios.post(`api/uploadFile`,

        form, config).then((res) => {

        if (res.data.status === 'success') {

            console.log('上传成功')

        }

    })