File Uploader Component for Vue.js using Firebase Storage

FileUploader.vue

<template>

  <div>
    <input type="file" multiple accept="image/*" @change="detectFiles($event.target.files)">
    <div class="progress-bar" :style="{ width: progressUpload + '%'}">{{ progressUpload }}%</div>
  </div>

</template>

<script>

import { storage } from '../firebase'
export default {
  data () {
    return {
      progressUpload: 0,
      file: File,
      uploadTask: '',
      downloadURL: ''
    }
  },
  methods: {
    detectFiles (fileList) {
      Array.from(Array(fileList.length).keys()).map( x => {
        this.upload(fileList[x])
      })
    },
    upload (file) {
      this.uploadTask = storage.ref('imagenes/articulos').put(file);

      this.uploadTask.then(snapshot => {
        this.downloadURL = this.uploadTask.snapshot.downloadURL;
        this.$emit('url', this.downloadURL)
      })
    }
  },
  watch: {
    uploadTask: function() {
      this.uploadTask.on('state_changed', sp => {
        this.progressUpload = Math.floor(sp.bytesTransferred / sp.totalBytes * 100)
      })
    }
  }
}
</script>

<style>
.progress-bar {
  margin: 10px 0;
}
</style>