uploadfile.vue

<template>
  <div id="app">
    <input type="file" ref="file" v-on:change="handleUpload()"/>
    <button v-on:click="uploadFile()">Upload</button> <br>
  </div>
</template>

<script>
import axios from 'axios'
export default {
    data () {
        return {
          file: ''
        }
    },
    methods: {
        handleUpload() {
            this.file = this.$refs.file.files[0]
        },
        uploadFile() {
            const formData = new FormData()
            formData.append("file", this.file)
            axios.post('http://localhost:5000/upload', formData, {
                headers: {
                    "Content-Type": "multipart/form-data"
                }
            }).then(response => {
                console.log(response.data)
            }).catch(error => {
                console.log(error)
            })
        }
    }
}
</script>