axios+Vue实现上传文件显示进度功能

<div id="app">
<h4>上传文件：</h4>
   <p class="input-zone">
    <span v-if="filename">{{filename}}</span>
    <span v-else>+请选择文件上传+</span>
 <input type="file" name="file" value="" placeholder="请选择文件" @change="upload" multiple="multiple" />
   </p>
  <p>上传进度：</p>
   <div class="progress-wrapper">
    <div class="progress-progress" :style="uploadStyle"></div>
    <div class="progress-rate">{{(uploadRate*100).toFixed(2)}}%</div>
   </div>
  </div>

.input-zone { width: 500px; color: blue; font-size: 14px; position: relative; }
   .input-zone input[type='file'] { opacity: 0; width: 100%; height: 100%; position: absolute; left: 0; top: 0; z-index: 2; }
  .progress-wrapper { position: relative; height: 50px; border-radius: 5px; background-color: lightgrey; }
   .progress-wrapper .progress-progress { position: absolute; left: 0; top: 0; height: 100%; width: 0%; border-radius: 5px; background-color: darkturquoise; z-index: 1; }
   .progress-wrapper .progress-rate { position: relative; text-align: center; font-size: 14px; line-height: 50px; height: 100%; z-index:2;}

var app = new Vue({
   el: "#app",
   data: {
    uploadRate: 0,
    filename: '',
    uploadStyle: {
     width: '0%'
    }
   },
   methods: {
    upload: function (e) {
     var vm = this;
     var formData = new FormData();
     formData.append("name", "Alax");
     for (var i = 0; i < e.target.files.length; i++) {
      var file = e.target.files[i]; //取第1个文件
      formData.append("file", file);
      vm.filename = file.name;
      console.log(file);
     }
     var config = {
      headers: { 'Content-Type': 'multipart/form-data' },
      onUploadProgress: function (e) {
       console.log("进度：");
       console.log(e);
       //属性lengthComputable主要表明总共需要完成的工作量和已经完成的工作是否可以被测量
       //如果lengthComputable为false，就获取不到e.total和e.loaded
       if (e.lengthComputable) {
        var rate = vm.uploadRate = e.loaded / e.total; //已上传的比例
        if (rate < 1) {
         //这里的进度只能表明文件已经上传到后台，但是后台有没有处理完还不知道
         //因此不能直接显示为100%，不然用户会误以为已经上传完毕，关掉浏览器的话就可能导致上传失败
         //等响应回来时，再将进度设为100%
         vm.uploadRate = rate;
         vm.uploadStyle.width = (rate *100).toFixed(2)+ '%';
        }
       }
      }
     };
     axios.post("/ajaxPage/VueUpload.aspx?method=upload", formData, config)
      .then(function (data) {
       console.log(data);
       var json = data.data; //后台实际返回的结果
       if (json.result) {
        vm.uploadRate = 1;
        vm.uploadStyle.width = '100.00%';
       } else {
        alert(json.msg);
       }
      })
      .catch(function (err) {
       console.log(err);
      });
    }
   }
  })